Chinese authorities are carrying out forced sterilisations of women in an apparent campaign to curb the growth of ethnic minority populations in the western Xinjiang region, according to research published Monday.

The report, based on a combination of official regional data, policy documents and interviews with ethnic minority women, has prompted an international group of lawmakers to call for a United Nations investigation into China's policies in the region.

The move is likely to enrage Beijing, which has denied trampling on the rights of ethnic groups in Xinjiang, and which on Monday called the allegations "baseless".

The country is accused of locking more than one million Uighurs and other mostly Muslim minorities in re-education camps. Beijing describes the facilities as job training centres aimed at steering people away from terrorism following a spate of violence blamed on separatists.

Now a report by Adrian Zenz, a German researcher who has exposed China's policies in Xinjiang, says Uighur women other ethnic minorities are being threatened with internment in the camps for refusing to abort pregnancies that exceed birth quotas.

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 sterilization 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 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. (AFP)