Human rights advocates are calling on the United Nations to address reports of Chinese internment camps holding 1 million Muslim minorities in Northwest China.

The call comes shortly before a review of China’s human rights record on November 6 by the U.N. Human Rights Council. The last review of China’s human rights was in 2013.

Ex-detainees have said these camps include abuse and political indoctrination, the Guardian has reported.

Researchers believe an estimated 1 million Muslim Uighurs have been detained at these camps. British diplomats, who visited Xinjiang in August, have confirmed those numbers, according to officials.

“The Human Rights Council must send an unequivocal message to the Chinese government that their campaign of systematic repression in the XUAR (Xinjiang Uighur autonomous region), including the arbitrary detention of up to 1 million people, must end,” said Patrick Poon, China researcher at Amnesty International.

Poon was among numerous human rights advocates at an activist forum on China held in Geneva Nov. 2.  

Sharon Hom, executive director Human Rights in China, also attended the forum.

“The detention of over a million ethnic Uighurs is a tipping point for the international community. They really can’t look the other way now,” Hom told Reuters.

Dolkun Isa, president of the World Uighur Congress, stressed the urgency of the situation.

“In the last five years, generally the human rights situation in China has been getting worse, particularly in east Turkestan (Xinjiang) and Tibet, there has been an unimaginable deterioration,” he told Reuters.

The Washington Post reported that the chairman of China’s Xinjiang Uighur Autonomous Region, Shohrat Zakir, stated earlier this month that the camps do exists but are a “vocational education and training program” aimed at curbing terrorism.

China has said that it is responding to threats in Xinjiang posed by Islamist militants and separatists. However, it has rejected accusations of mistreatment in Xinjiang or Tibet.