The United States and more than 30 countries have condemned what they call China's "horrific campaign of repression" against its Uyghur Muslims minority in the western region of Xinjiang.

Key points: Beijing is alleged to be waging widescale repression of its Uyghur Muslim minority

Beijing is alleged to be waging widescale repression of its Uyghur Muslim minority The US said UN members had a responsibility to speak up about human rights attacks

The US said UN members had a responsibility to speak up about human rights attacks Muslim governments have been silent over allegations of China's Uyghur mistreatment

The move came at an event on the sidelines of the annual United Nations General Assembly (UNGA), which was denounced by China on Tuesday.

Deputy Secretary of State John Sullivan said the UN and its member states had "a singular responsibility to speak up when survivor after survivor recounts the horrors of state repression".

Mr Sullivan said it was incumbent on member states to ensure the world body was able to closely monitor human rights abuses by China and added that it must seek "immediate, unhindered and unmonitored" access to Xinjiang for the UN High Commissioner for Human Rights.

Bordered by eight countries, Xinjiang is China's largest province. ( Supplied: Google Maps )

He said the event was co-sponsored by Canada, Germany, the Netherlands and Britain, and was joined by more than 30 UN states, representatives of the European Union and more than 20 non-governmental organisations, as well as Uyghur victims.

"We invite others to join the international effort to demand and compel an immediate end to China's horrific campaign of repression," he said.

"History will judge the international community for how we respond to this attack on human rights and fundamental freedoms."

UN human rights chief Michelle Bachelet has repeatedly pushed China to grant the body access to investigate reports of disappearances and arbitrary detentions, particularly of Muslims in Xinjiang.

When asked about the US's efforts at the UNGA, Chinese Foreign Ministry spokesperson Geng Shuang told reporters in Beijing that Washington should "stop interfering in others' domestic affairs in the name of human rights".

Uyghur detainees at "re-education" camps are forced to listen to "deradicalisation" speeches. ( Supplied: RFA )

"Lately the US, in disregard of China's opposition, has been using religion and human rights as a cover to slander and smear China's Xinjiang policies and interfere in China's internal affairs again and again," Mr Shuang said.

"The US chooses not to see China's efforts and progress in counterterrorism and deradicalisation, and not to hear the voice of justice on Xinjiang by relevant countries and individuals."

Up to one million detained, millions more monitored

While US officials have ramped up criticism of China's measures in Xinjiang, it has refrained from responding with sanctions, amid on-again, off-again talks to resolve a bitter, costly trade war.

On Monday, US President Donald Trump called for an end to religious persecution at another event on the sidelines of the UN gathering.

He reiterated his comments in a speech to the General Assembly's gathering of world leaders.

"Americans will never … tire in our effort to promote freedom of worship and religion. We want and support religious liberty for all," he said.

Mr Trump said religious freedom was under growing threat around the world, but fell short of specifically mentioning the Uyghur situation.

The UN said at least 1 million ethnic Uyghurs and other Muslims have been detained in what China describes as "vocational training centres" to stamp out extremism and give people new skills.

Workers walk by the perimeter fence of what is officially known as a vocational skills education centre in Dabancheng. ( Reuters: Thomas Peter )

Mr Sullivan said the United States had received "credible reports of deaths, forced labour, torture, and other cruel, inhumane, or degrading treatment" in the camps.

He said there were also many reports that the Chinese Government forces detainees to renounce their ethnic identities as well as their culture and religion.

In February, the ABC reported that China was closely monitoring around 2.5 million people with a technology known as a "Muslim tracker", after the discovery of an insecure database managed by a company contracted by Chinese police that uses artificial intelligence for facial recognition, crowd analysis and personal verification.

Muslim Governmental peak body silent on Uyghurs

China's Uyghurs are a minority Muslim ethnic group who speak a language stemming from the Turkic language family. ( Reuters: Thomas Peter )

Washington has criticised other countries, including some Muslim states, for not doing enough or for backing China's approach in Xinjiang.

The Organisation for Islamic Cooperation — the inter-governmental peak body for the Muslim world — has been repeatedly criticised for failing to speak up China's alleged human rights abuses against Muslims in Xinjiang.

In March, its Council of Foreign Ministers produced a resolution that commended "the efforts of the People's Republic of China in providing care to its Muslim citizens" in spite of mounting evidence of discrimination against China's Uyghur Muslims.

This week, its publicly listed meeting agenda items to discuss on the sidelines of the UNGA failed to mention the treatment of Uyghurs, despite its mention of the treatment of Muslims in Myanmar, the Palestinian territories and Indian Kashmir.

Rishat Abbas, the brother of Uyghur physician Gulshan Abbas, who was abducted from her home in Urumqi in September 2018, told delegates at the UN event that "millions of Uyghurs were becoming collateral damage to international trade policies".

She said this "enabled China to continue to threaten our freedoms around the world, enable it to continue its police state."

ABC/Reuters