China on Tuesday called for U.N. human rights chief Michelle Bachelet to respect its sovereignty, after she urged it to allow monitors into the restive far western region of Xinjiang and expressed concern about the situation there.

China has said Xinjiang faces a serious threat from Islamist militants and separatists who plot attacks and stir up tension between the mostly Muslim Uighur minority who call the region home and members of the ethnic Han Chinese majority.

Last month, a United Nations rights panel said it had received credible reports that up to one million ethnic Uighurs may be held in extralegal detention in Xinjiang, and called for them to be freed.