On a remote site at the edge of the Gulf of Oman, thousands of migrant laborers from Bangladesh, India and Pakistan are at work in 103-degree heat, toiling in shifts from dawn until nightfall to build a new city, a multibillion-dollar project backed by Oman’s oil-rich government that has an unusual partner: former President Donald J. Trump.

Mr. Trump’s name is plastered on signs at the entrance of the project and in the lobby of the InterContinental Hotel in Muscat, the nearby capital of Oman, where a team of sales agents is invoking Mr. Trump’s name to help sell luxury villas at prices of up to $13 million, mostly targeting superrich buyers from around the world, including from Russia, Iran and India.

Mr. Trump has been selling his name to global real estate developers for more than a decade. But the Oman deal has taken his financial stake in one of the world’s most strategically important and volatile regions to a new level, underscoring how his business and his politics intersect as he runs for president again amid intensifying legal and ethical troubles.

Interviews and an examination by The New York Times of hundreds of pages of financial documents associated with the Oman project show that this partnership is unlike any other international deal Mr. Trump and his family have signed.

• The venture puts Mr. Trump in business with the government of Oman, an ally of the United States with which Mr. Trump and his son-in-law, Jared Kushner, cultivated ties while in office and which plays a vital diplomatic role in a volatile region. The Omani government is providing the land for the development, is investing heavily in the infrastructure to support it and will get a cut of the profits in the long run.

• Mr. Trump was brought into the deal by a Saudi real estate firm, Dar Al Arkan, which is closely intertwined with the Saudi government. While in office, Mr. Trump developed a tight relationship with Saudi leaders. Since leaving office, he has worked with Saudi Arabia’s sovereign wealth fund to host the LIV golf tour and Mr. Kushner, received a $2 billion infusion from the Saudi fund for his investment venture.

• Mr. Trump’s company, the Trump Organization, has already brought in at least $5 million from the Oman deal. Under its terms, Trump Organization will not put up any money for the development, but will help design a Trump-branded hotel, golf course and golf club and will be paid to manage them for up to 30 years, among other revenue.

• The project could also draw scrutiny in the West for its treatment of its migrant workers, who during the first phase of construction are living in compounds of cramped trailers in a desertlike setting and are being paid as little as $340 a month, according to one of the engineers supervising the work.

Mr. Trump’s business ties in the Middle East have already been under intense scrutiny. Federal prosecutors who brought criminal charges against him in the case stemming from his mishandling of classified documents issued subpoenas for information about his foreign deals and the agreements with the Saudi-backed LIV Golf tour.

During his presidency, Mr. Trump’s family business profited directly from money spent at his Washington hotel by foreign governments including Saudi Arabia, just one example of what ethics experts cited as real or perceived conflicts of interest during his administration. His stake in the project in Oman as he runs for president again only focuses more attention on whether and how his own financial interests could influence foreign policy were he to return to the White House.

“This is as blatant as it comes,” said Virginia Canter, the chief ethics counsel to Citizens for Responsibility and Ethics in Washington, a nonprofit group that has investigated Mr. Trump’s foreign deals. “How and when is he going to sell out U.S. interests? That is the question this creates. It is the kind of corruption our founding fathers most worried about.”

Not ‘the Hamptons of the Middle East’

In February, Eric Trump, the former president’s son who is overseeing the project for Trump Organization while also playing a role in his father’s re-election campaign, traveled to Oman to visit the cliff-side site where the golf course will soon be built. He met with executives from Dar Al Arkan, the Saudi firm, as well as top government officials from Oman who control the land.

“It’s like the Hamptons of the Middle East,” Eric Trump said in an interview, declining to address other questions about the project.

Oman, in fact, is nothing like the Hamptons. It is a Muslim nation and absolute monarchy, ruled by a sultan, who plays a sensitive role in the Middle East: Oman maintains close ties with Saudi Arabia and its allies, but also with Iran, with which it has considerable trade.

As a result, Oman has often served as an interlocutor for the West with Iran, including in the lead-up to the 2015 agreement the Obama administration and other Western governments negotiated with Iran to slow its move to build nuclear weapons, a deal Mr. Trump later abandoned. In recent months, Oman has hosted indirect talks to try to ease tensions between Iran and the United States.

Oman is also a buyer of weapons from the United States, including Lockheed Martin’s F-16 fighter jets and a Raytheon-manufactured missile system that it agreed to purchase last year. Mr. Trump, while at the White House, had sent Mr. Kushner to Oman in 2019 to meet with Sultan Qaboos bin Said, then the nation’s monarch, to discuss the Arab-Israeli dispute.

Mr. Trump later reached out to Haitham bin Tariq Al Said, who took over as the new sultan in 2020, to praise “the success of the first eight months” of his rule and to discuss ways to “strengthen the Oman-U.S. bilateral economic partnership,” according to a White House summary of the call.

Mr. Trump did not pursue any new international real estate deals while in office, but his search for deep-pocketed international partners picked up when he left the White House in January 2021, his reputation at home tarnished by the Jan. 6 assault on the Capitol. And it was through Dar Al Arkan, the Saudi real estate company, that Mr. Trump and his family firm got into the Oman project.

The government of Oman had chosen Dar Al Arkan to run the second phase of the Yiti project, which covers a vast stretch of coastline east of the capital city. Hashil bin Obaid Al Mahrouqi, the chief executive of the Omani government agency that oversees the Yiti project, said it was Dar Al Arkan’s choice to bring in Mr. Trump, but he added that international brands like Mr. Trump’s would help bring global attention — and sales — to the project.

“Helping us to accelerate the delivery of the project, accelerate also the return of the project, to accelerate the selling of the project,” Mr. Al Mahrouqi said, speaking from the conference room of a beachfront W Hotel that his agency also developed in Oman. “What is good for the project is good for us.”

Mr. Trump was on hand to close the deal in New York in November, just before he announced his 2024 presidential bid. Executives from the Saudi real estate company visited Trump Tower and showed off designs for the project, and Eric Trump signed paperwork confirming the deal.

“Our partnership with Trump will distinguish our first project in Oman and put it on the global map,” Yousef Al Shelash, the chairman of Dar Al Arkan, said in a statement issued as the deal was signed.

Neither Dar Al Arkan nor the Trump Organization would say how much the Trump family would be paid. In previous international deals, the family has traditionally taken a fee in exchange for the use of its name, a separate fee to manage the hotel and golf properties, and a percentage of the profits on the sale of Trump-branded villas, if the prices hit a goal.

Links to Foreign Governments

In Oman, the government’s contribution to the Yiti project starts with the land: It has set aside nearly 3,000 acres along the Gulf of Oman for the project, a quarter of which it has turned over to the Saudi-run Dar Al Arkan. The Omani government will be paid back over time for the land, and get a cut of the profits from the project, according to a detailed description of the deal made public in a financial filing in London.

Separately, the government of Oman is investing hundreds of millions of dollars to upgrade highways and utilities, and to sponsor the first phase of the project, which includes a Nikki Beach resort hotel that is already being built adjacent to where the Trump golf course and hotel are planned.

“What you see in front of you — that’s a billion dollars’ worth of investments,” said Ammar Al Kharusi, the head of development at the Oman government’s tourism agency, as he stood on the edge of a cliff that overlooked the first phase of the Yiti project, where hundreds of workers toiled below, as countless trucks and at least a dozen cranes hauled in and lifted loads of steel and other building supplies to construct this new metropolis.

Next door is the second phase — called Oceana at Aida — that will be built by Dar Al Arkan on a desertlike plateau towering nearly 450 feet above the Gulf of Oman, offering extraordinary views.

The area historically has been known for what is called Wadi Mayh, a ravine that remains dry most of the year, but whose raging waters during the region’s occasional rains have left elaborate rock formations that create spectacular natural vistas. Dar Al Arkan and the Trump Organization now want to build luxury hotels, golf course and townhouses overlooking the austere landscape.

Dar Al Arkan was founded nearly three decades ago by Saudi real estate executives who bought up land for future housing developments, and it eventually became a large-scale home builder itself.

It maintains extremely close ties with the Saudi government.

Dar Al Arkan is one of the country’s most important beneficiaries of a decision more than a decade ago by Saudi Arabia to pump in billions of dollars of government funds to help create a modern, mortgage-backed housing industry in an effort to expand homeownership. It is also a major investor in Saudi Home Loans Company, which has profited as government dollars flow into the mortgage industry.

Dar Al Arkan more recently moved into international luxury real-estate development, this time through a London-based subsidiary it set up called DarGlobal.

DarGlobal is teaming up with luxury brands like Missoni, Versace, Lamborghini — as well as the Trump family — on projects outside Saudi Arabia targeting international buyers. DarGlobal is targeting buyers who will pay as much as a 30 percent premium for a “branded” townhouse and can often buy their units with cash, according to a confidential company document obtained by The Times.

“There is a big wealth concentration in the world, which means that those people will more and more demand more exclusive products and more exclusive projects,” Ziad El Chaar, DarGlobal’s chief executive, told real estate developers in France this year.

Mr. El Chaar had worked with the Trump family in Dubai, building a Trump International Golf Club. Pleased with that project, he asked the Trump family to join him in Oman, in what will be DarGlobal’s largest international project, worth an estimated $4 billion.

The 30-year agreement between DarGlobal and the Trump family designates the Trump Organization as the hotel manager that will “direct the management and operation of a world-class, superluxury hotel to be constructed by Dar Oman within its Aida project in Oman.” The deal puts the Trump company in charge of the hotel budget, its restaurants and any retail stores. The Trump Organization will set prices and market the hotel once it opens under the name Trump International Hotel Oman.

It will have similar management rights over the 18-hole golf course and golf club, which will be known as Trump International Golf Club Oman. There were also be over 200 “Trump branded residential villas,” according to one company document published in January, and marked confidential.

The Trump family, the agreement says, will not have to commit its own money to the project, but it will have detailed oversight including reviewing a “model room” that DarGlobal will build to sign off on the design.

“Dar Oman will design, develop, construct, equip and furnish the hotel, at its sole cost and expenses, in accordance with the specifications, standards and requirements issued from time to time by the hotel manager,” the financial documents say, referring to the Trump Organization.

Working in the Heat

More than 1,000 migrant laborers are busy in the searing heat building the first phase of the Oman government’s Yiti project. Next door, at the Aida site, where the Trump-branded phase of the project will eventually rise, work on the roads is just beginning.

The army of workers, in orange, blue or yellow overalls, move deliberately, many of them with their heads covered with towels and other fabrics stuffed under their hard hats to try to protect themselves from the heat, routinely above 100 degrees, during 10-hour shifts. They live mostly in trailer camps adjacent to the construction site, or they arrive in fleets of buses that run through the billowing clouds of dust that blow through.

Like other Middle Eastern nations, Oman has drawn scrutiny for its treatment of foreign workers. In a report last year, the State Department listed “labor exploitation of foreign migrants” as among the human rights issues it is monitoring in Oman.

Some low-skilled migrant workers in fields including construction “faced working conditions indicative of forced labor,” said the report, which went on to say that Oman has “appropriate” safety and health labor standards that, it noted, an advocacy group said were not always enforced for foreign workers.

One recent afternoon, the migrant workers came marching out of the site of the first phase during a shift change, walking right past a giant sign promising “Coming Soon to Aida, Trump International Golf Club, Oman” showing renderings of a carefully manicured golf course to be carved from the desertlike land.

In tiny print at the bottom of the site, it also said, “Trump International Golf Club Oman is not owned, developed or sold by Donald J. Trump, Donald J. Trump Jr., Eric Trump,” noting that this site was run by DarGlobal.

“It’s too hot — too hot,” said Mathan Mp, 38, who is from Tamil Nadu, the southernmost state of India, said as he took a break from supervising dozens of workers at the project site. “But we came for work. We have a time schedule. We have to finish the project.”

Omani officials said they would closely monitor working conditions for the laborers, adding that during the hottest weeks of the summer the workers would not be at the site in the middle of the day.

Executives at DarGlobal, Dar Al Arkan and the Trump Organization declined to comment.

The Trump-branded project is being built just above the seaside village of Yiti, where there are now more donkeys, goats and stray cats in the streets than people, as many have moved away as the construction projects have accelerated.

The few remaining residents do not know a great deal about Mr. Trump, having only a general impression of him as a rich businessman and politician.

Htim Talbi, whose family has lived in Yiti for six decades and remains in one of the few occupied homes in the dusty town, said he harbored a far-off dream that he might somehow afford one of the luxury townhouses.

“Trump — he is your king from America,” Mr. Talbi said, after inviting a visitor to his village inside to an air-conditioned room to sit on the floor and share a pot of tea. “Welcome to Oman.”