As the Chinese government tracked and persecuted members of predominantly Muslim minority groups, technology giant Alibaba taught its corporate customers how they could play a part.

Alibaba’s website for its cloud computing business showed how clients could use its software to detect the faces of Uighurs and other ethnic minorities within images and videos, according to pages on the site that were discovered by the surveillance industry publication IPVM and shared with The New York Times. The feature was built into Alibaba software that helps web platforms monitor digital content for material related to terrorism, pornography and other red-flag categories, the website said.

The discovery could thrust one of the world’s most valuable internet companies into the storm of international condemnation surrounding China’s treatment of its Muslim minorities.