The UN committee's report called on Beijing to release members of the mainly Muslim minority, who live in the western region of Xinjiang, from "reeducation camps", where they are held in what the government claims is part of the struggle against terrorism.
But Beijing has hit back at the findings.
"These comments ... were based on so-called information that is yet to be verified and has no factual basis," Chinese foreign ministry spokesperson Hua Chunying said at a regular press briefing.
The World Uighur Congress on Friday accused China of building a concentration camp in its autonomous Xinjiang region. .
"This is the 21st century and we still have a concentration camp after we said no after World War II,” Shahrezad Ghayrat, a member of the World Uighur Congress in Germany told RFI.
Lost contact with relatives
The majority-Muslim ethnic minority has long complained of state repression and activists say it is getting worse.
"Uighurs in the diaspora started to lose contact with their family members as early as 2017 and late 2016," comments Ghayrat, who adds that she hasn't seen or heard her family members "for the past two years."
"The majority of Uighurs share the same feelings. They cannot just contact their family. There’s a social media app called WeChat, basically our family members have deleted us from it,” she says.
The app allows users to pledge their loyalty to the China's ruling Communist Party and its leaders, as a way of upholding "ethnic harmony", a prized ideal of the state.
But critics see this as an attempt to suppress the Uighurs' identity and that's precisely what's going on inside what the UN describes as "internment camps," says Ghayrat.
“It’s a political indoctrination camp, where they get brainwashed, denounce their religion, their Uighur identity," she comments.
A former inmate in one of the interment camps said Muslims were forced to eat pork and drink alcohol, acts which are forbidden by their religion.
"They get up at five in the morning to chant songs and they have to read the Chinese policies, laws, and memorise them. If they don’t pass the test they get punished," she said.
War on terror and war on religion
Xinjiang has seen intermittent violence - followed by crackdowns - for years. The most notable was the 2009 riots in Urumqi.
"There is a bit of evidence for the Chinese claims that there is a serious religious extremist problem in Xinjiang," says Roderic Wye, an associate fellow at Chatham House's Asia Pacific Programme, and author of a blog on the Uighurs.
Wye adds that the crackdown on the Uighurs should be seen in the context of the war on terror.
"China wants to take its own measures to deal with domestic and international terrorism and there have been a few examples of Uighurs who have been found in Afghanistan and elsewhere joining jihadi groups," he told RFI.
But he reckons that the fight against religious extremism is being used as a pretext to combat religion altogether.
“The Chinese have always been suspicious, both of nationalism in Xinjiang and religious expression in Xinjiang and it’s not just the Uighurs," he comments.
Ghayrat agrees. "They’re atheist. For them, they don’t want you to believe in anything greater than the party, the Chinese party.”
China’s actions have not gone unnoticed.
On Thursday US lawmakers slapped sanctions on those Chinese officials involved in the internment of Uighur Muslims, to which Beijing retorted: "the US has no right to criticise China on this issue."
"It’s not going to change Chinese behaviour at all, I’m afraid," Wye says. "The fact is that the Chinese are now in a much more powerful position than they were 20 or 30 years ago. They are much less responsive to international pressure, especially if it comes from the West."
And Muslim-majority countries are not fighting the Uighurs' corner, according to Wye.
"Turkey was a great refuge for many of the Uighurs since they are a Turkish speaking people but currently Turkey seems to be much closer to China than it was," he points out.
The UN report urged China to release all detainees immediately.
"They have not released anyone yet," regrets the World Uighur Congress' Ghayrat.
"They’re still building more [camps]. If we do not take action quickly then we are looking at half of the population being arbitrarily detained."
And Beijing spokesperson Hua showed no sign of a change of line.
"The sense of security and the fulfilment of people in Xinjiang has been greatly enhanced," she said. "As for all the preventive security measures we've taken, many countries around the world do the same."