The United Nations will be judged by how it addresses China's persecution of ethnic minorities, diplomats and human rights advocates charged on the sidelines of the body's General Assembly, calling for forceful action after a report raised the spectre of "crimes against humanity."

For years, rights watchdogs and journalists have exposed the brutal treatment of Uyghurs and other mostly Muslim ethnic groups in the far western region of Xinjiang, where China is accused of a ruthless campaign of torture, sexual assault and ethnic cleansing. Those accusations have been widely accepted in the West, but were given a new imprimatur with the landmark report released last month by the UN human rights office.

Police officers stand at the outer entrance of the Urumqi Number 3 Detention Center in Dabancheng in western China's Xinjiang Uyghur Autonomous Region. Photo / AP

"Inaction is no longer possible," Fernand de Varennes, the United Nations' special rapporteur on minority rights said at a forum sponsored by the Atlantic Council and Human Rights Watch, as world leaders descend on New York. "If we allow this to go unpunished, what kind of message is being propagated?"

Jeffrey Prescott, a deputy US ambassador to the United Nations, suggested the integrity of the institution was at stake in its response to China.

"How these atrocities are addressed goes ultimately to the credibility of that system, to the credibility of our international system itself," he said. "It's deeply disheartening to see a country that has been so central to the creation of the modern UN system, and enjoys its status as a permanent member of the Security Council, so profoundly violating its commitments."

The UN report on China's alleged abuses was released in the final minutes of the last day in office of Michele Bachelet, now the former UN High Commissioner for Human Rights. Its release was believed to have been long delayed. Bachelet never explained the timing.

China responded to its release with fury, calling it "a patchwork of false information" and portraying it as a fabrication cooked up by Western nations. It issued a lengthy rebuttal and vowed to stop cooperating with the UN's human rights office, and Chinese diplomats are now lobbying others to thwart the possibility of further scrutiny of its campaign in Xinjiang.

People stand in a guard tower on the perimeter wall of the Urumqi Number 3 Detention Center in Dabancheng in western China's Xinjiang Uyghur Autonomous Region. Photo / AP

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Rob Roe, Canada's ambassador to the United Nations, called China's reaction unsurprising and said new action was merited.

"We need to deal with this question. We need to deal with the question of what further sanctions will be required. We need to deal with the question of what further steps could be taken to respond to the extent of this crisis," he said.

The UN's report was drawn, in part, from interviews from more than two dozen former detainees, and others familiar with conditions at eight detention centres, who described being beaten, prevented from praying and being forced to perform sex acts on guards. It said the evidence could constitute "crimes against humanity" but made no mention of genocide, which the United States and other countries have accused China of committing.

Prince Zeid Ra'ad Al Hussein, the immediate predecessor to Bachelet as UN High Commissioner for Human Rights, said his successor deserved credit for publishing the report, but said it was a "shortcoming" not to refer to the abuses as genocide. Likewise, he criticised it for not calling for the establishment of a formal UN commission of inquiry.

"To be silent is to be an accomplice," he said.

Rayhan Asat, a Uyghur lawyer who works for the Atlantic Council and whose brother is imprisoned in Xinjiang, urged the world to insist that action be taken, not just against China, but companies which profit off its abuses.

"We should not let the Chinese government off the hook by normalising what the state did," she said, "because at the end of the day, this is state violence."