Leaked government documents outlining the need to prevent escape, double lock doors and constantly monitor detainees in China's network of internment camps in Xinjiang refute Beijing's defence of "vocational education centres" in the region, experts say.

Obtained by the International Consortium of Investigative Journalists (ICIJ) and published by 17 media outlets worldwide on Sunday, the documents show the strict protocols governing life in the camps in Xinjiang, where an estimated one million Uighurs and other mostly Muslim minorities are held.

In one document, local officials are told to monitor inmates at all times -- including during toilet breaks -- to prevent escape.

Staff are also banned from befriending inmates and engaging in "personal interactions" to prevent "collusion", the document read.

"It shatters (the Chinese Communist Party's) CCP's narrative about these camps as benign vocational training centres where Uighurs and other Chinese Muslim(s) willingly undertake training," said James Leibold, an expert on ethnic relations in China and a professor at Melbourne's La Trobe University.

Instead, the documents outline "in the Party's own words... the calculated, coercive, and extrajudicial nature of these detentions," he told AFP.

The leak comes one week after The New York Times reported, based on more than 400 pages of internal papers it had obtained, that Chinese President Xi Jinping ordered officials to act with "absolutely no mercy" against separatism and extremism in a 2014 speech following a Uighur militant attack on a train station.

After initially denying their existence, China acknowledged that it had opened "vocational education centres" in Xinjiang aimed at preventing extremism by teaching Mandarin and job skills.

In light of ICIJ's investigation, China's foreign ministry remained dismissive, with spokesman Geng Shuang on Monday accusing "some media" of "smearing China's counter-terrorism and anti-extremism efforts in Xinjiang".

The Chinese embassy in London denied such documents existed, telling the Guardian, one of the partners in publishing the memos, they were "pure fabrication and fake news".

Former detainees describe Xinjiang facilities as indoctrination camps that are part of a campaign to eradicate Uighur culture and religion.

The latest leak consists of a list of guidelines for running the camps approved by Xinjiang's security chief in 2017, along with intelligence briefings that show how police use data collection and artificial intelligence to select residents for detention.

Officials were ordered to keep strict secrecy about the "highly sensitive" centres, with staff forbidden from bringing mobile phones or cameras into "teaching and management areas", according to one document.

Referring to detainees as students who must "graduate" from the camps, the guidelines lay out how staff should manage their day-to-day lives, such as by ensuring "timely haircuts and shaves", while also emphasising that detainees are barred from having cellphones, according to an English translation of the memo posted by ICIJ.

"Students... may not contact the outside world apart from during prescribed activities," the memo reads, adding that staff should "strictly manage students requesting time off." If indeed the so-called students "really need to leave the training centre due to illness or other special circumstances, they must have someone specially accompany, monitor and control them."

The memo says inmates should be judged based on a points system that measures "ideological transformation, study and training, and compliance with discipline."

"There must be full video surveillance coverage of dormitories and classrooms free of blind spots, ensuring that guards on duty can monitor in real-time, record things in detail, and report suspicious circumstances immediately," it adds.

ICIJ's documents also bolstered existing reports on the "Integrated Joint Operation Platform" (IJOP), a surveillance app previously reported on by Human Rights Watch.

According to a leaked bulletin from June 2017, more than 15,000 people in Xinjiang were sent to "education and training" because of IJOP, while around 2,000 were placed under "preventative surveillance." Even Xinjiang residents outside the country were subject to surveillance, the documents showed.

According to another bulletin from June 2017, the Chinese government recorded 1,535 individuals from Xinjiang with foreign nationality who had applied for Chinese visas.

Those "for whom suspected terrorism cannot be ruled out" and had cancelled their Chinese citizenship were to be deported, while those who had not were "first be placed into concentrated education and training", it said.

According to the memo, "students" must stay in detention for at least one year, though that rule was not always enforced, former inmates told ICIJ.