China may have committed "crimes against humanity" in its discriminatory treatment of Uyghur and other Muslim groups in the far-western Xinjiang autonomous region, a U.N. report found Wednesday, with the global body's human rights chief recommending measures to rectify the situation.

"The extent of arbitrary and discriminatory detention of members of Uyghur and other predominantly Muslim context of restrictions and deprivation more generally of fundamental rights enjoyed individually and collectively, may constitute international crimes, in particular crimes against humanity," the report said.

File photo shows Uyghur workers and others in a sewing factory in China's Xinjiang region in May 2021. (Kyodo)

The findings, released just minutes before U.N. High Commissioner for Human Rights Michelle Bachelet's term ended Wednesday, were met with a fierce response from Beijing.

Its permanent mission to the United Nations in Geneva issued a document in which it claimed the assessment was "based on the disinformation and lies fabricated by anti-China forces" and "wantonly smears and slanders China" as well as interferes in the country's internal affairs.

Chinese Foreign Ministry spokesman Wang Wenbin said in Beijing Thursday that China rejects the publication of the report, calling it "completely illegal and void." He insisted the assessment was "orchestrated and produced" by the United States and other Western forces.

"It is a patchwork of disinformation that serves as a political tool for the United States and other Western countries to strategically use Xinjiang to contain China," Wang said.

In Tokyo, Chief Cabinet Secretary Hirokazu Matsuno said Japan appreciates the release of the U.N. report and underlined the importance of freedom, basic human rights and the rule of law being guaranteed in China.

Bachelet, a former president of Chile, visited the Xinjiang region in May amid allegations by some Western nations that China has committed "genocide" there. The United States and other democratic nations have imposed sanctions or similar steps against China based on the claims.

The paper said "serious human rights violations" have been committed in Xinjiang in the context of the Chinese government's application of strategies against terrorism and extremism, with those placed in "vocational education and training centers" subject to torture, abuse and inhuman treatment between 2017 and 2019.

The U.N. human rights office said it interviewed 40 Uyghur, ethnic Kazakh and Kyrgyz people and 26 said they had been detained or had worked in various facilities across the autonomous region since 2016.

The report said no single interviewee among those who had been placed in the facilities said they could freely exit them or go home for a visit.

At those facilities, all interviewees observed a significant security presence and guards armed with guns.

None were informed of the length of their stays when they were taken to the facilities, the document said, which it inferred means such treatment amounts to "a form of deprivation of liberty" without any apparent legal basis.

China insists the vocational training centers were established to combat terrorism and religious extremism and denies any human rights violations in Xinjiang.

The report urged China to take "prompt steps to release all individuals arbitrarily deprived of their liberty," clarify the whereabouts of missing individuals and "urgently repeal all discriminatory laws, policies and practices" against Muslim minorities in Xinjiang.

Wang indicated at a press conference that China will not follow such recommendations, saying Beijing "has every reason to say no" to the report.

He criticized the U.N. office for reducing itself to become "an accomplice of certain anti-China forces," alleging it made up the assessment "due to pressure from external forces out of political motives."

The U.N. office also sought support from the international community for efforts to improve the human rights situation in Xinjiang and urged countries not to return Uyghur and other predominantly Muslim minority refugees to China.

Bachelet, who became the first U.N. human rights chief to visit China in 17 years, admitted last week that she was under "tremendous pressure" over the publication of the report, with her office receiving letters expressing opposition to its release from about 40 countries.

The document was originally expected to be published earlier this year, but its release was repeatedly postponed. Gen Nakatani, special adviser to Japanese Prime Minister Fumio Kishida on human rights issues, was among those who had called for an early release of the report.