By Patricia Zengerle

WASHINGTON (Reuters) – A group of Democratic and Republican U.S. senators wrote to remote-control maker Universal Electronics (NASDAQ:) Inc on Wednesday about concerns the Arizona-based company could be implicated in mistreatment of Uyghur Muslims in China’s Xinjiang region.

The letter cited a Reuters report earlier this month that Universal struck a deal with authorities in Xinjiang to transport hundreds of Uyghur workers to its plant in the southern Chinese city of Qinzhou. There, workers live in segregated dormitories, are continuously surveilled by police and made to participate in government “education activities,” Reuters reported.

“We believe these conditions bear obvious signs of forced labor,” said Democratic Senators Bob Menendez and Jeff Merkley and Republican Senator Marco Rubio in the letter to Universal Electronics Chief Executive Paul Arling.

“We are especially troubled that Universal Electronics appears to have done little to investigate or remedy the situation,” the letter, which was seen by Reuters, added.

Universal Electronics told Reuters earlier this month the company currently employs 365 Uyghur workers at the Qinzhou plant. It said it treated them the same as other workers in China and it did not regard any of its employees as forced labor.

The Nasdaq-listed firm, which has sold its equipment and software to Sony (NYSE:), Samsung (KS:), LG, Microsoft (NASDAQ:) and other companies, also it does not conduct independent due diligence on where and how its workers are trained in Xinjiang. It said the arrangement is vetted by a third-party agent, which it declined to name, working with the Xinjiang government.

In the letter to Arling, the U.S. senators cited State Department findings that Chinese authorities use threats of physical violence, forcible drug intake, physical and sexual abuse, and torture to force detainees to work in adjacent or off-site factories or worksites.

The letter asked Universal Electronics to provide, no later than Nov. 5, information including the text of its 2019 agreement with the Xinjiang government regarding Uyghur laborers, the number of Uyghurs employed in China and documentation to support the company’s assertion that none of its labor is forced.

The senators also asked for details of employee training programs related to forced labor and human trafficking, records of audits of facilities in China and the content of any disclosure to shareholders about the use of transferred Uyghur laborers.