Now a report by Adrian Zenz, a German researcher who has exposed China's policies in Xinjiang, says Uighur women, among other ethnic minorities, are being threatened with internment in the camps for refusing to abort pregnancies that exceed birth quotas.
Mr Zenz's data-driven work -which uses public documents found by scouring China's internet - on the camps has previously been cited by experts on a UN panel investigating the facilities.
Women who had fewer than the legally permitted limit of two children were involuntarily fitted with IUDs, says the report.
It also reports that some of the women said they were being coerced into receiving sterilisation surgeries.
Former camp detainees said they were given injections that stopped their periods, or caused unusual bleeding consistent with the effects of birth control drugs.
Government documents studied by Mr Zenz also showed that women in some rural minority communities in the region received frequent mandatory gynaecological exams and bi-monthly pregnancy tests from local health officials.
Mr Zenz found that population growth in Xinjiang counties predominantly home to ethnic minorities fell below the average growth in primarily Han majority counties between 2017 and 2018, a year after the officially recorded rate of sterilisations in the region sharply overtook the national rate in 2016.
Uighur activists said China was using the internment camps to conduct a massive brainwashing campaign aimed at eradicating their distinct culture and Islamic identity.
China appears to be using coercive birth control in Xinjiang as part of a "wider game plan of ethno-racial domination," Mr Zenz wrote in the report.
"These findings raise serious concerns as to whether Beijing's policies in Xinjiang represent, in fundamental respects, what might be characterised as a demographic campaign of genocide" under UN definitions, Mr Zenz said in the report.
Foreign Minister Marise Payne said Australia had serious concerns about the treatment of Uighurs in China and had raised these directly with government counterparts.
"Our concerns are further compounded by the reports of enforced birth control measures and sterilisations targeting these groups," she said in a statement.
"We have raised our concerns about the situation in Xinjiang on multiple occasions with Chinese government officials, and I have discussed this issue directly with my counterpart, State Councilor Wang Yi."
The US State Department called the campaign "reminiscent of the abuses against members of ethnic and religious minority groups throughout the 20th century."
"We call on the Chinese Communist Party to immediately end these horrific practices and ask all nations to join the United States in demanding an end to these dehumanising abuses," Secretary of State Mike Pompeo, a frequent critic of Beijing, said in a statement.
The Inter-Parliamentary Alliance on China (IPAC), a group of North American, European and Australian members of parliament from a range of political parties, said in a statement it would push for a legal investigation on "whether or not crimes against humanity or genocide have taken place" in Xinjiang.
IPAC was formed in June with a stated mission of standing up against "challenges posed by the present conduct and future ambitions of the People's Republic of China."
Britain said it was aware of reports which "add to our concern about the human rights situation in Xinjiang".
"Of course we will be considering this report very carefully," junior foreign office minister Nigel Adams told parliament.
China's foreign ministry said the allegations were "baseless" and showed "ulterior motives."
Foreign ministry spokesman Zhao Lijian blasted media outlets for "cooking up false information on Xinjiang-related issues," saying at a regular press briefing that Xinjiang is "harmonious and stable."
The rights group World Uighur Congress said the report showed a "genocidal element of the CCP's (Chinese Communist Party) policies" and called in a statement for international action to confront China.