The United States has stepped up the blocking of imports of Chinese goods made in Xinjiang, but the top US anti-human trafficking official said that spotting slave-made goods is becoming increasingly complex.
Ambassador-at-Large John Richmond said reports that forced labor by the Chinese government had spread beyond Xinjiang to other provinces complicated the process of due diligence for global firms.
"It is increasingly difficult for well-intentioned international companies to track exactly which products in their supply chain are made with forced labor," Richmond told a Zoom call with journalists.
Richmond added that the United States would continue its efforts to connect companies with activists and non-profits to help call attention to abuses such as forced labor in China.
"US companies do not want to unwittingly support forced labor and neither do US consumers," Richmond said.
The Xinjiang region in northwest China is home to a large population of Uighur people, a Muslim minority that has faced mass detention in Chinese government camps.
An Australian think tank earlier this year found that tens of thousands of Uighurs were moved to work in factories in other parts of China.
Another program in rural Tibet, where workers are being transferred into military-style training centers, was reported by Reuters in September and defended by officials in Chinese-administered Tibet this week.
China's government has denied the mistreatment of the Uighurs in Xinjiang and the presence of forced labor in Tibet.
A representative for the Chinese Embassy in the United States said all workers in Xinjiang entered into contracts with employers and that the issue of forced labor there was a rumor created by anti-China media.
"Such a rumor has not a shred of fact in it," the Chinese representative said via email.
The US government's criticism of China comes at a time of bilateral trade tensions between the two countries.