China tech giant Alibaba offered face-recognition software that could enable users to identify Uighurs, a report said, making it the latest Chinese company embroiled in the country's controversial treatment of the Muslim minority.

Alibaba's website for its cloud-computing business showed how clients could use the software to detect the facial features of Uighurs and other ethnic minorities within images and videos, according to The New York Times.

The references, later removed by Alibaba, appeared on web pages seen by US-based surveillance research firm IPVM and shared with the newspaper, its report said.

Alibaba said the function was only used in testing.

"The ethnicity mention refers to a feature/function that was used within a testing environment during an exploration of our technical capability. It was never used outside the testing environment," Alibaba Cloud said in a statement to AFP.

Just last week, IPVM said Chinese telecoms company Huawei had been involved in testing facial recognition software that could send alerts to police when it recognised Uighur faces.

Huawei has denied the claims.

But two days later, Barcelona's World Cup-winning footballer Antoine Griezmann said he was ending an endorsement deal with Huawei over the revelation.

China has come under intense international criticism over its policies in Xinjiang, where rights groups say as many as one million Uighurs and other mostly Muslim minorities have been held in internment camps.

Beijing initially denied the camps' existence but now calls them vocational training centres aimed at stamping out terrorism and improving employment opportunities.

Surveillance spending in Xinjiang has risen sharply in recent years, with facial recognition, iris scanners, DNA collection and artificial intelligence deployed across the province in the name of preventing terrorism.

Alibaba is the leader in China's huge e-commerce sector and has expanded into cloud computing, bricks-and-mortar stores and delivery services, as well as operating overseas.

But it and other Chinese tech companies are coming under increasing foreign scrutiny over allegations of digital collusion with China's state security apparatus.

The US Trump administration has imposed an escalating series of sanctions against Huawei and hinted at applying pressure on other companies, possibly including Alibaba, amid rising Sino-US tensions.