China said Wednesday it was "willing to engage" with the UN Human Rights Office over its northwestern region of Xinjiang but rejected efforts to "smear" its policies there.

The UN rights office (OHCHR) warned on Tuesday that "problematic" policies persist in Xinjiang, two years after its bombshell report citing possible "crimes against humanity" in the region.

China has been accused of incarcerating more than a million Uyghurs and other Muslim minorities in Xinjiang, charges Beijing vehemently rejects.

The OHCHR demanded this week that Chinese authorities "undertake a full review" of the legal requirements pertaining to national security and counter-terrorism, as well as guarding minorities against discrimination.

Beijing's foreign ministry defended its policies in the region at a news briefing on Wednesday.

"Xinjiang enjoys social stability, economic development and its people live in peace and prosperity," spokesman Lin Jian said.

"China is willing to engage in constructive exchanges and cooperation with the United Nations Office of the High Commissioner for Human Rights on the basis of mutual respect," he said.

He urged the rights office to "perform its duties impartially and objectively" and warned it against the "politicisation of human rights and divisive confrontational actions".