The courage of former inmates and relatives, and the diligence of academics, journalists and other researchers, has brought a terrible secret into plain view. As the evidence piled up of the mass extrajudicial detention of Muslim Uighurs, Kazakhs and others in China’s north-western region of Xinjiang, it was met with silence or denial from Beijing. When experts told a UN panel this August that as many as a million could be held, a Chinese official insisted that: “There is no such thing as re-education centres.”

Still the satellite imagery, public documents and frightening personal testimonies amassed. With a UN human rights council meeting approaching next month, China suddenly announced that under revised legislation, local governments in Xinjiang could “educate and transform” people influenced by extremism at “vocational training centres”. This does not make the detentions themselves lawful, says one expert on Chinese law: “People are simply taken away.” But Beijing is now actively promoting the programme as an altruistic attempt to improve lives as well as stabilising the region, preventing further violent attacks. State media has shown “students” in uniforms playing ping pong and folk dancing, and learning skills such as hairdressing. The chairman of the regional government enthuses that the centres are air-conditioned, offer nutritious free meals and show that “life can be so colourful”.

This humane idyll – a free summer camp with careers assistance – is in stark contrast to the harsh regime recorded by others. This week, a report by AFP based on tendering and other official documents found such facilities ordering razor wire, spiked clubs and restraint devices known as “tiger chairs”. Former detainees have described political indoctrination and abuse. While the government official suggested that inmates are “suspected of minor criminal offences”, released prisoners describe people being held for having relatives abroad, reciting a religious verse at a funeral or failing to pay a bill. And as parents disappear into camps, children are being taken from families and placed in de facto orphanages.

The programme appears to be accelerating: the BBC suggests that the largest known camp now has room for up to 130,000 inmates and would be one of the world’s largest prisons even on a very conservative estimate. Outside, people live under the region’s extraordinary digital surveillance – including a vast network of cameras, facial recognition systems and the mass collection of biometric data – as well as under close human view.

A disturbing account by an ethnographer this week detailed how more than a million Chinese officials have been sent out to stay with households in a “Becoming Family” campaign. Officials portray it as an attempt to win hearts, including through help with poverty alleviation. But they are also told to gather information on their hosts, report on “unusual situations” and carry out political propaganda work. One regional manual tells workers to inform their “little brothers and sisters” that they have been monitoring all internet and phone communications, and recommends targeting children for information. No private space of family and faith remains.

These inconvenient facts have until recently been met largely with silence, including from Muslim countries. That is beginning to change. The US has raised the prospect of sanctions; the new UN rights chief, Michelle Bachelet, has pressed the issues; others are voicing concerns. We now know what is happening. Who will act?