Jared Kushner, the son-in-law of Donald J. Trump, confirmed on Friday that he was closing in on major real estate deals in Albania and Serbia, the latest example of the former president’s family doing business abroad even as Mr. Trump seeks to return to the White House.

Mr. Kushner’s plans in the Balkans appear to have come about in part through relationships built while Mr. Trump was in office. Mr. Kushner, who was a senior White House official, said he had been working on the deals with Richard Grenell, who served briefly as acting director of national intelligence under Mr. Trump and also as ambassador to Germany and special envoy to the Balkans.

One of the proposed projects would be the development of an island off the coast of Albania into a luxury tourist destination.

A second — with a planned luxury hotel and 1,500 residential units and a museum — is in Belgrade, the capital of Serbia, at the site of the long-vacant former headquarters of the Yugoslav Army destroyed in 1999 by the NATO bombings, according to a member of Parliament in Serbia and Mr. Kushner’s company.

These first two projects both involve land now controlled by the governments, meaning a deal would have to be finalized with foreign governments.

A third project, also in Albania, would be built on the Zvërnec peninsula, a 1,000-acre coastal area in the south of Albania that is part of the resort community known as Vlorë, where several hotels and hundreds of villas would be built, according to the plan.

Mr. Kushner’s participation would be through his investment firm, Affinity Partners, which has $2 billion in funding from Saudi Arabia’s Public Investment Fund, among other foreign investors. In a statement, an official with Affinity Partners said it had not been determined whether the Saudi funds might be a part of any project Mr. Kushner is considering in the Balkans.

“We are very excited,” Mr. Kushner said in an interview. “We have not finalized these deals, so they might not happen, but we have been working hard and are pretty close.”

Mr. Kushner set up his investment company after he left his White House job as a senior adviser. He capitalized on relationships he had built in government negotiating in the Middle East, which included a close relationship with Crown Prince Mohammed bin Salman, the de facto ruler of Saudi Arabia.

Mr. Kushner ended up securing the $2 billion from the sovereign wealth fund of Saudi Arabia and hundreds of millions of dollars more from wealth funds in the United Arab Emirates and Qatar. He has taken few public steps so far to actually invest large chunks of this money.

Mr. Grenell also made valuable connections while in government, including some that appear to have given the Kushner team an inside track for investments in the Balkans. During his time in the Trump administration, Mr. Grenell worked on resolving disputes between Serbia and Kosovo.

These discussions indirectly involved Albania, as most citizens of Kosovo are ethnic Albanians and Albania plays a role in the regional discussions.

Mr. Grenell has remained close with Mr. Trump since the former president left office, defending him publicly and speaking to him regularly.

Mr. Grenell has said privately that he hopes to be secretary of state in a second Trump administration, according to a person who has discussed the matter with Mr. Grenell and who described the conversations on the condition of anonymity.

Mr. Grenell, in an interview, declined to address on the record any interest in potentially taking a post as secretary of state. He said only that he had not decided whether he would join any future Trump administration.

Robert Weissman, president of Public Citizen, which tracked business deals it considered conflicts of interest during the Trump administration, said these planned deals were unethical and would only raise new questions about the Trump family, particularly if Mr. Trump was re-elected.

“At this point in the election cycle Jared Kushner should freeze any new investment plans,” Mr. Weissman said. “This particular investment plan seems to involve the worst of every corrupt tendency of the Trump administration and Trump family.”

The Trump family’s involvement in foreign business deals became a major focus during Mr. Trump’s term, with critics ultimately suing and alleging that the family was illegally profiting from foreign payments — referred to as emoluments in the Constitution — while Mr. Trump was in office. These cases were dismissed as moot by the Supreme Court when Mr. Trump left office, but they could be reopened if he was back in the White House.

Since leaving office, Mr. Trump has become a partner in a development project in Oman, a deal he was brought into by a Saudi real estate firm that has ties to the Saudi government.

Mr. Kushner rejected any suggestion that he was getting preferential treatment because of his time in the government, or that any of the work was connected to the former president.

“No one is ‘giving’ me deals,” said Mr. Kushner, who insisted he was not planning to return to Washington should his father-in-law win the presidency again. “I operate fairly meticulously, and these investments will create a lot of value for the local communities, our partners and our investors.”

Representatives for Mr. Trump did not respond to multiple emails seeking comment.

Mr. Kushner and his wife, Ivanka Trump, have largely stayed away from Mr. Trump’s political activities since the Jan. 6, 2021, attack on the Capitol.

The New York Times first approached Mr. Kushner on Wednesday morning about his prospective projects in the Balkans. He initially declined to answer questions, responding only after he disclosed his plans to Bloomberg News on Friday.

Mr. Kushner and Ms. Trump visited Albania twice since Mr. Trump left office. They traveled the country with Mr. Grenell, and even met with Albania’s prime minister.

Mr. Kushner and Ms. Trump, along with Mr. Grenell, have been focused in part on Sazan, a Mediterranean island in the south of Albania that until the end of the Cold War had been used by the Soviet Union and the Communist-led government of Albania as a secretive military base for submarines. The plan is to build a luxury hotel and villas on the island.

The rugged two-square-mile island has hundreds of Cold War-era bunkers and tunnels designed to withstand nuclear attack and has been largely vacant since the end of the Soviet Union. But it is only a half-hour by speedboat from Vlorë, a resort destination in southern Albania where the government of Saudi Arabia is already spending money to improve electricity service and other public utilities to help promote tourism in Albania.

Mr. Grenell, a former Fox News contributor and media consultant, has been working closely with Mr. Kushner and his investment firm.

Mr. Grenell has been vocal about his efforts to turn relationships he built in Albania and elsewhere in the Balkans into personal profits. He has returned to the region repeatedly and met with hotel industry executives, as well as Albania’s prime minister, Edi Rama.

“We are looking for opportunities to invest through foreign investment in the Balkans, but more specifically in Albania, and the Albanian coast is wonderful,” Mr. Grenell said in one of a series of television and newspaper interviews he has done in Albania in the last three years.

The day-to-day management of the projects would be handled by Asher Abehsera, a California-based real estate developer who has done projects in Brooklyn with Mr. Kushner, and who traveled to the Balkans with Mr. Grenell and Mr. Kushner to check out the development sites, Mr. Kushner said.

Mr. Grenell added in a nearly 90-minute television interview in Albania last year that there was nothing wrong with his deal making because he was now out of government. “I’m working on projects, private equity projects, that I get to make money on,” he said. “No one should ever apologize for wanting to make money.”

Last July, Mr. Grenell, along with Ivanka Trump and Mr. Kushner, also met with Mr. Rama in Tirana, the capital of Albania, and they were all photographed together.

Mr. Rama has been pushing for nearly a decade to open Sazan up to redevelopment as a tourist destination, as well as looking for other ways to attract foreign investors to Albania to expand its tourist economy.

Auron Tare, a former member of the Parliament in Albania who has served as an adviser to Mr. Rama, took Ms. Trump and Mr. Kushner to Sazan Island in 2021 as part of a visit of Albania that included a cruise on a yacht and a helicopter trip across the coast.

Mr. Tare, in an interview, said he discussed with Mr. Kushner and Ms. Trump the desire to develop Sazan, but to do so in a way that would preserve its history and environment.

Mr. Kushner and Mr. Grenell have been working closely with a billionaire Albanian business executive named Shefqet Kastrati and his son, Musa Kastrati. Their investments include a concession to run the international airport in Tirana, a chain of gas stations in Albania and hotels and other businesses, according to business associates and Mr. Kushner.

“They have helped us understand the cost of construction and how to operate locally,” Mr. Kushner said in an interview.

In October 2022, Shefqet Kastrati bought a $7.5 million house in Indian Creek, Fla., land records show, a property that is near where Ms. Trump and Ms. Kushner now live. The Kastrati family also last year purchased a hotel in the Brickell section of Miami for $55 million from the Qatari royal family.

Musa Kastrati, in an interview, said that the role his family company would play in Mr. Kushner’s Albanian projects was still not clear, but that it would probably involve helping build some of the complexes. Mr. Kastrati also confirmed that he visited Mar-a-Lago, Mr. Trump’s Florida resort and residence, in December 2022 with Mr. Grenell and that he also briefly met Mr. Trump when the former president arrived as they were having dinner. Mr. Kastrati said he did not discuss the potential deal with Mr. Trump.

Mr. Grenell has repeatedly taken to Instagram and other social media accounts to promote tourism in Albania and to praise Mr. Rama, the prime minister.

“I support Rama’s vision for the Balkans,” Mr. Grenell said in a television interview in 2021, after he met with another hotel industry executive in Albania named Irfan Hysenbelliu. “I love Albania and I invite U.S. investors in the country.”

The government of Saudi Arabia recently announced that it was looking for ways to increase its investment in Albania, first by helping build water, electricity and sewer services next to beach areas in Vlorë, which is the launching point to Sazan and where a new international airport is already being built. It has said it wants to invest up to $300 million in the nation.

Earlier this month, Saudi officials traveled to Albania to announce the creation of what they are calling the Saudi-Albania Business Council “to forge a new economic partnership between the two countries,” including in tourist projects. The Saudi chairman of the group, Abdulrahman Al-Mufarreh, did not respond to requests for comment.

Michael S. Schmidt contributed reporting.