U.N. human rights chief Volker Turk on Monday said China was violating fundamental rights in its Xinjiang and Tibet regions and called on Beijing to change course.

Turk, who has been criticized for not challenging China strongly enough over human rights, also asked Beijing to release rights defenders arrested under the "vague" offense of "picking quarrels and making trouble."

He called on Beijing to implement recommendations made by his office and other human rights bodies "in relation to laws, policies and practices that violate fundamental human rights, including in the Xinjiang and Tibet regions."