A senior US senator on Tuesday accused US firms of wilfully ignoring "horrific" forced labour conditions in China's Xinjiang region and called on the Commerce Department to stop American companies and consumers buying goods produced by such labour.

In a letter to Commerce Secretary Wilbur Ross, Democratic Senator Bob Menendez (above) said recent reports indicated a wide array of US companies, including Apple, Kraft Heinz, Coca-Cola, and the Gap, had sourced, or continued to source, goods from Xinjiang.

"Moreover, there are consistent reports that US companies fail to undertake basic labour and human rights assessments in Xinjiang, in essence wilfully ignoring the horrific conditions of forced labour in Xinjiang," Menendez, the ranking member of the Senate Committee on Foreign Relations, said in the letter.

"In failing to uphold their responsibilities to vet their supply chains, these companies may be complicit in the mass repression of Uyghurs, ethnic Kazakhs, Kyrgyz, and members of other Muslim minority groups," he said.

The firms Menendez mentioned did not immediately respond to requests for comment.

The United Nations estimates more than a million Muslim Uyghurs have been detained in camps in Xinjiang in recent years. China denies it violates Uyghur rights and says the camps are designed to stamp out terrorism and provide vocational skills.

Menendez, who has called for sanctions on China over the issue, also requested information about US government contractors who source cotton from China, which produces 84 percent of its cotton in Xinjiang.

"The use of materials that are manufactured using forced labour is unacceptable for products in US markets," he said in the letter.

An Australian think tank said in a report earlier this month that tens of thousands of ethnic Uyghurs have been transferred to work in factories across China supplying 83 global brands in conditions "that strongly suggest forced labour."

Nike, which was included in that report, said in a statement on its website that while the company "does not directly source products from the Xinjiang Uighur Autonomous Region", it had been conducting due diligence with its suppliers in China to identify and assess potential risks related to employment of people from the region.

On Monday, the Washington-based Fair Labor Association, which conducts due diligence for major multinational firms, said it was "deeply troubled by credible reports of forced labour and other violations of fundamental rights in Xinjiang."

"We have directed our affiliates to review their direct and indirect sourcing relationships, identify alternative sourcing opportunities, and develop timebound plans to ensure that their sourcing is in line with the FLA's principles," it said.

- Reuters