Lawmakers sent letters to Intel and Nvidia seeking information on the sale of computer chips allegedly used by China to conduct mass surveillance.

Republican Senator Marco Rubio and Democratic Representative Jim McGovern on Tuesday sent letters to Intel Corp and Nvidia Corp seeking information on the sale of advanced computer chips allegedly used by China to conduct mass surveillance on Uighurs in the country’s remote Xinjiang region.

Rubio is chairman of the Senate Foreign Relations subcommittee which oversees human rights, and McGovern chairs the Congressional-Executive Commission on China.

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The letters were sent to the chief executives of the companies, who were asked to respond to questions about their exports to China.

The executives were also asked whether they knew their technology would be used to support surveillance activities conducted by China’s police forces and whether they took steps to ensure their products were not used for human rights abuses or to compromise U.S. national security.

The United Nations has previously estimated that more than a million Muslims have been detained in camps in the Xinjiang region. The U.S. State Department has accused Chinese officials of subjecting Uighur Muslims to torture, abuse “and trying to basically erase their culture and their religion.” Earlier this year, U.S. President Donald Trump signed legislation calling for sanctions over the repression of China’s Uighurs.

Originally published at Equities