A partnership between Ford Motor and a major Chinese battery maker is facing scrutiny by Republican lawmakers, who say it could make an American automaker reliant on a company with links to forced labor in China’s Xinjiang region.

In a letter sent to Ford on Thursday, the chairs of the House Select Committee on the Chinese Communist Party and the House Ways and Means Committee demanded more information about the partnership, including what they said was a plan by Ford to employ several hundred workers from China at a new battery factory in Michigan.

Ford announced in February that it planned to set up the $3.5 billion factory using technology from Contemporary Amperex Technology Ltd., known as CATL, the world’s largest maker of batteries for electric vehicles. CATL produces about a third of electric vehicle batteries globally and supplies General Motors, Volkswagen, BMW, Tesla and other major automakers.

Ford has defended the partnership, saying it will help diversify Ford’s supply chain and allow a battery that is less expensive and more durable than current alternatives to be made in the United States for the first time, rather than imported.

But lawmakers, who previously criticized the partnership, cited evidence that CATL had not relinquished its ownership of a company it helped set up in Xinjiang, where the United Nations has identified systemic human rights violations.

CATL publicly divested its share of the company, Xinjiang Zhicun Lithium Industry Company, in March, after its deal with Ford was announced. But the shares were bought by an investment partnership in which CATL owned a partial stake and a former CATL manager who holds leadership roles in other companies owned by the battery maker, corporate records show.

The circumstances of the sale raise “serious questions about whether CATL is attempting to obscure links to forced labor,” wrote Representatives Mike Gallagher of Wisconsin, the chairman of the select committee, and Jason Smith of Missouri, the chairman of the Ways and Means Committee.

The lawmakers, citing details of Ford’s licensing agreement that are on file with the select committee, also criticized the automaker’s commitment to employ several hundred Chinese workers. Employees from China would set up and maintain CATL’s equipment at the Michigan factory until about 2038, the lawmakers said. The factory is expected to employ 2,500 U.S. workers, Ford has said.

“Ford has argued that the deal will create thousands of American jobs, further Ford’s ‘commitments to sustainability and human rights’ and lead to American battery technology advancements,” they wrote. “But newly discovered information raises serious questions about each claim.”

T.R. Reid, a spokesman for Ford, said the company was going through the letter and would respond in good faith. He said that human rights were fundamental to how Ford did business, and that the automaker was thorough in assessing such issues.

“There has been an awful lot said and implied about this project that is incorrect,” Mr. Reid said. “At the end of the day, we think creating 2,500 good-paying jobs with a new multibillion investment in the U.S. for great technology that we’ll bring to bear in great electric vehicles is good all the way around.”

CATL’s collaboration with Ford could be a bellwether for the electric vehicle industry in the United States. Critics have labeled the agreement a “Trojan horse” for Chinese interests and called for scuttling the partnership. If it succeeds, they say, reliance on Chinese technology could become the norm for the U.S. electric vehicle industry.

Ultimately, China’s control over key technologies like batteries could leave the United States “in a far weaker position,” said Erik Gordon, a clinical assistant professor at the University of Michigan’s Ross School of Business.

“The profit margins go to the innovators who provide the advanced technology, not the people with screwdrivers that assemble the advanced technology,” he said.

But CATL and other Chinese companies have battery technology not readily available from suppliers in the United States or Europe. The Michigan plant would be the first in the United States to produce so-called LFP batteries that use lithium, iron and phosphate as their main active materials.

They are heavier than the lithium, nickel and manganese batteries currently used by Ford and other automakers but less expensive to make and more durable, able to withstand numerous charges without degrading. They also do not use nickel or cobalt, another battery material, which are often mined in environmentally damaging ways, and sometimes with child labor.

Without the most advanced or least expensive batteries, U.S. carmakers could fall behind Chinese rivals like BYD that are pushing into Europe and other markets outside China. Americans may also have to pay more for electric cars and trucks, which would slow sales of vehicles that do not emit greenhouse gases.

A battery unveiled by CATL last year delivers hundreds of miles of driving range after a charge of just 10 minutes.

“The hard truth is that the Chinese took a huge gamble on electric vehicles and plopped down over a trillion Chinese dollars and subsidies on this industry, and it just so happens that gamble came up all aces,” said Scott Kennedy, a China expert at the Center for Strategic and International Studies.

“If you decide not to partner with a very large battery maker, then you’re essentially committing to delaying the U.S. energy transition,” he added.

Ford plans to use batteries made with CATL technology in lower-priced versions of vehicles like the Mustang Mach-E and F-150 Lightning pickup. The least expensive version of Tesla’s Model 3 sedan comes with an LFP battery that CATL is widely reported to have supplied.

For decades, Western companies have had a monopoly on the world’s most advanced technologies, and have sought access to the Chinese market while also safeguarding their intellectual property.

But China’s dominance in electric vehicle batteries, as well as in the production of solar panels and wind turbines, has flipped that dynamic. It has created a particularly tricky dilemma for the Biden administration and other Democrats, who want to reduce the country’s reliance on China but also argue that the United States must quickly make a transition to cleaner energy sources to try to mitigate climate change.

The solar and electric vehicle battery industry’s exposure to Xinjiang further complicates the situation. The Biden administration has condemned the Chinese government for carrying out genocide and crimes against humanity in the region.

The United States last year barred imports of products made in whole or in part in Xinjiang, saying companies operating in the region are not able to ensure that their facilities are free of forced labor.

In 2022, CATL and a partner registered a lithium processing company in the region called Xinjiang Zhicun Lithium Industry Company, which promoted plans to become the world’s largest producer of lithium carbonate, a key battery component.

Through a series of subsidiaries and shareholder relationships, that Xinjiang lithium company has financial ties to a Chinese electricity company, Tebian Electric Apparatus Stock Company, or TBEA, according to records that The New York Times reviewed through Sayari Graph, a mapping tool for corporate ownership. TBEA has participated extensively in so-called poverty alleviation and labor transfer programs in Xinjiang that the United States considers a form of forced labor.

While the Chinese government argues that labor transfer and poverty alleviation programs are aimed at improving living standards in the region, human rights experts say that they are also directed at pacifying and indoctrinating the population, and that Uyghurs and other minority groups there cannot say no to these programs without fear of detention or punishment.

CATL did not respond to a request for comment. In December, it told The Times that it was a minority shareholder in the Xinjiang company and strictly prohibited any form of forced labor in its supply chain.

The Republican lawmakers also raised concerns about whether batteries made at Ford’s Michigan plant would qualify for tax credits that the Biden administration was offering consumers who bought electric vehicles as part of the Inflation Reduction Act.

The law prohibits “foreign entities of concern” — like companies in China, Russia, Iran or North Korea — from benefiting from government tax credits. But because Ford is licensing CATL technology for the plant — rather than forming a joint venture, as has often been the case with automakers and battery suppliers — the batteries made in Michigan may still qualify for those incentives.

The Biden administration has not yet clarified exactly how the restriction on foreign entities will be applied. But Ford officials said they had been in conversation with the administration about the Michigan plant, and were confident that the partnership would qualify for all of the law’s benefits.

“We think batteries built by American workers in an American plant run by the wholly owned subsidiary of an American company will and should qualify,” Mr. Reid, the Ford spokesman, said.