International companies cannot responsibly operate in Xinjiang and should leave the western Chinese region due to forced labor concerns, a U.S. Labor Department official said.

The U.S. government says Chinese officials continue to commit genocide and crimes against humanity against Uyghurs and other Muslim minorities in Xinjiang, and rights groups have pressured Western companies there to audit their operations over forced labor concerns. China’s government vehemently denies allegations of abuses.

Thea Lee, deputy undersecretary for international affairs at the Labor Department, told a U.S. congressional hearing that Beijing had made it “essentially illegal” to conduct independent human rights audits in Xinjiang.

“If it is impossible to do that, then the only responsible thing to do is not to operate in that atmosphere,” Lee told the Congressional-Executive Commission on China, without naming individual companies.