Four companies and a manufacturing facility in northwestern China have been blocked from shipping their products to the United States.
The move was taken by the US owing to the firms' suspected reliance on forced labour from people detained as part of a massive campaign against ethnic minorities in the region.
The US Customs and Border Protection (CPB) issued orders freezing imports from companies that produce cotton, clothing and computer parts in the Xinjiang region of northwestern China.
The Chinese authorities have reportedly detained more than one million people in detention camps as part of the
crackdown.
CBP also halted imports of hair products made at a manufacturing facility where authorities believe Uighurs and other ethnic minorities are forced to work.
Ken Cuccinelli, the Acting Deputy Secretary of the Department of Homeland Security, dismissed the notion that the facility is a vocational center, as has been portrayed by Chinese authorities.
The US issues the orders under the 1930 Tariff Act, which prohibits imports produced with prison or slave labour to ensure fair competition with US manufacturers and keep tainted products out of the supply chain.