The United States (US) on Tuesday promised enforcement as a landmark ban took effect on most imports from Xinjiang, the Chinese region where rights groups say the Uyghur people are being forced into slave labour.
The Uyghur Forced Labor Prevention Act, which will be felt especially in the textile industry, took effect six months after it was signed into law by President Joe Biden following bipartisan support in Congress.
"We are rallying our allies and partners to make global supply chains free from the use of forced labour," Secretary of State Antony Blinken said in a statement.
The US Customs and Border Protection service, which will enforce the new law, issued guidance that said it would presume products from Xinjiang involve forced labour and are therefore banned unless businesses can document otherwise.
The act "requires that importers demonstrate due diligence, effective supply chain tracing and supply chain management measures to ensure that they do not import any goods made, in whole or in part, by forced labour," its advisory said.
It said it would look at the complete supply chain and not exempt goods shipped from other parts of China or third countries.
An estimated 20 percent of garments imported into the US each year include some cotton from Xinjiang, according to labour rights groups.
The vast western region is also a major centre of tomatoes canned for export.
Senator Marco Rubio, a Republican hawk who teamed up with liberal Democrats to push for the legislation, called the act "the most significant change in America's relationship with China since 2001."
"No longer will we look at images of bareheaded prisoners in shackles and blindfolds, lined up like animals for slaughter, and shrug," he wrote in an opinion piece for Real Clear Politics.
'Undermines Free Market Principles'
China entered the World Trade Organization (WTO) in 2001, helping usher in soaring growth as it became the manufacturing hub for the world.
US policymakers across party lines have gradually come to reject their bet that trade integration would moderate Beijing, which the Biden administration has identified as the top global competitor of the US.
China again voiced anger over the trade ban and said it went against global efforts to decrease inflation and stabilize supply chains.
"The act is solid evidence of the US's arbitrariness in undermining international economic and trade rules," foreign ministry spokesman Wang Wenbin said.
"The US move is against the trend of the times and bound to fail."
But Omer Kanat, executive director of the Uyghur Human Rights Project, called the law a "huge win" for the movement and said it would push other governments to take similar action.
Rights groups, citing witness accounts, say that well more than one million Uyghurs and other predominantly Muslim Turkic-speaking people have been locked up in re-education camps in a bid to integrate them forcibly into China's Han majority.
Beijing denies the charges and says it is providing vocational training to reduce the allure of Islamist extremism following violence.