Chinese police have started gathering blood types, DNA samples, fingerprints and iris scans from millions of people in its Muslim-majority Xinjiang province to build a massive citizen database, according to report by activist group Human Rights Watch (HRW).

The report, published Wednesday, said that officials are collecting the data from citizens between the ages of 12 and 65 years old using a variety of methods. Authorities are gathering DNA and blood types through free medical checkups, and HRW said it is was unclear if patients were aware that their biometric data was being collected for the police during these physical exams.

According to the report, citizens authorities have flagged as a potential threat to the regime, and their families—named "focus personnel"—are forced to hand over their DNA regardless of age.

So far, 18.8 million citizens have participated in the medical checkups, called "Physicals for All" by the government, according to an article by a state news agency Xinhua on November 1.

"Xinjiang authorities should rename their physical exams project 'Privacy Violations for All,' as informed consent and real choice does not seem to be part of these programs," said Sophie Richardson, China director at HRW.