The U.S. sanctioned four Chinese officials, including a member of the Communist Party’s politburo, as well as the Xinjiang Public Security Bureau, in restrictions announced on Thursday.

The sanctioned individuals include Chen Quanguo, a politburo member and Xinjiang province party secretary, according to a statement from the Treasury Department. The others include Huo Liujun, Wang Mingshan and Zhu Hailun.

All four people are listed as being based in Xinjiang, the Chinese province where officials have forcibly detained Muslim Uighurs in a move widely criticized by senior U.S. officials and human rights groups.