PARIS (AFP) - French magistrates have opened an inquiry into allegations four fashion groups, including Uniqlo and the owner of Zara, profited from forced labour of the Uighur minority in China, a judicial source said on Thursday (July 1).

Magistrates at the national anti-terror prosecutor's office in Paris are probing claims the multinational companies are complicit in crimes against humanity, the source said, confirming a report on the Mediapart investigative website.

The case is based on a complaint lodged in April by the anti-corruption group Sherpa, the French branch of the Clean Clothes Campaign, and the Uighur Institute of Europe, as well as by a Uighur woman who had been held in a camp in Xinjiang, China.

They accused Inditex, the Spanish owner of Zara and other top brands, Uniqlo, the French fashion group SMCP, and the footwear manufacturer Skechers of using cotton produced in the Xinjiang region.

Rights groups believe at least one million Uighurs and other mostly Muslim minorities have been incarcerated in camps in the Xinjiang region, where China is also accused of forcibly sterilising women and imposing forced labour.

The United States says "genocide" has been inflicted on the Uighurs and other Muslim minorities in the region, while Beijing has denied all allegations of abuses and has insisted its policies in Xinjiang are necessary to counter violent extremism.

The US has announced import bans on a handful of companies operating in Xinjiang, including the solar panel maker Hoshine Silicon Industry.

Several major consumer brands including Uniqlo, H&M, Nike and Adidas announced last year that they would stop buying cotton from the region, leading to boycott calls in China.

Inditex disputed that it had used cotton from Xinjiang.

"The group has strict traceability controls which have allowed us to determine that the allegations in the complaint are unfounded," a company representative told AFP.

The company has a "zero tolerance policy for forced labour" and has "procedures in place that guarantee that practice doesn't exist in our supply chain", the representative added.

Uniqlo, which has taken a public position against the forced labour of Uighurs, is alleged to have sourced cotton from the Anhui province were thousands of Uighur workers have been transferred.

SMCP is alleged to be a shareholder in a firm with factories in Xinjiang, but the company refuted that and said it would work with investigators.