Amazon, Microsoft, Google, and other U.S. entities have been accused of providing web services to blacklisted Chinese surveillance companies, according to a report Thursday. These firms were found to be using their technology to aid “China’s campaign of repression, mass arbitrary detention, and high-technology surveillance against Uighurs, Kazakhs, and other members of Muslim minority groups” and have been blacklisted from accessing American tech as of October 2018.

The report came from Top10VPN, a London-based outlet dedicated to researching privacy in the Internet Age. It found that these major companies, and some smaller U.S. firms, have been providing “essential web services” to these Chinese outfits, including website hosting email services, and authentication software.

“Through providing essential web services to these controversial companies, U.S. firms are playing a part in the proliferation of highly invasive surveillance products that have the potential to undermine human rights around the world,” said Simon Migliano, Top10VPN’s head of research.

Amazon and Google are specifically accused of providing services to blacklisted companies, Dahua Technology and Hikvision. Microsoft is allegedly providing services to two major A.I. startups, SenseTime and Megvii. Overall, Google was found to have supported the most companies at nine, followed by Amazon with seven, and Microsoft with four. 

Alongside these tech juggernauts, smaller companies like GoDaddy, NortonLifeLock, Stackpath, and GeoTrust are among the other U.S. companies named in Top10VPN’s report. Twitter and Facebook were also mentioned for providing these blacklisted firms with content delivery systems.

These companies have been accused by the U.S. government of aiding the Chinese government in its detention of Muslim groups in Xinjiang, an autonomous region on China’s westernmost edge. Approximately 1.5 million Muslims have been held in detention camps and subjected to widely condemned human rights abuses. Some of these camps have reportedly even engaged in “re-education” therapies.