China has created a DNA database for the whole population of a Muslim region that has been blighted by violence, a report said.
Authorities have collected DNA and other biometric data from the whole of the western region of Xinjiang, where hundreds have been killed in the past few years.
Violence has been rife in the region between Uighurs, a mostly Muslim people, and ethnic majority Han Chinese, which Beijing blames on Islamist militants.
Human Rights Watch denounced the government's campaign as a gross violation of international norms in their report.
The unrest has fuelled a sweeping security crackdown there, including mass rallies by armed police, tough measures that rights advocates say restrict religious and cultural expression, and widespread surveillance.
Authorities will collect DNA from the region that has been blighted by violence 
Chinese soldiers march on the streets of Urumqi in China's far west Xinjiang province 
Police are responsible for collecting pictures, fingerprints, iris scans and household registration information, while health authorities should collect DNA samples and blood type information as part of a "Physicals for All" programme, the New York-based group said in a statement, citing government a document.
Human Rights Watch's China director Sophie Richardson said: "The mandatory databanking of a whole population's biodata, including DNA, is a gross violation of international human rights norms, and it's even more disturbing if it is done surreptitiously, under the guise of a free health care program."
According to the Xinjiang-wide plan posted online by the Aksu city government in July, main goals for the campaign include collecting the biometric data for all people between the age of 12 and 65, and verifying the region's population for a database.
"Blood type information should be sent to the county-level police bureaus, and DNA blood cards should be sent to the county police bureaus for inspection," the plan said.
Police are responsible for collecting pictures, fingerprints, iris scans and household registration information 
Data for "priority individuals" should be collected regardless of age 
Data for "priority individuals" should be collected regardless of age, it said, using a term the government has adopted to refer to people deemed a security risk.
Government workers must "earnestly safeguard the peoples' legal rights", plan said, but it made no mention of a need to inform people fully about the campaign or of any option for people to decline to take part.
Xinjiang officials could not be reached for comment.
Health authorities collect DNA samples and blood type information 
Crime Finger Print
Authorities have collected DNA and other biometric data from the whole of the western region of Xinjiang 
Chinese Foreign Ministry spokesman Lu Kang, asked about the report by Human Rights Watch, accused the group of making "untrue" statements.
He told a regular news briefing in Beijing the general situation in the region was good.
Human Rights Watch cited an unidentified Xinjiang resident saying he feared being labelled with "political disloyalty" if he did not participate, and that he had not received any results from the health checks.
State media, reporting on the campaign checks, have said participation was voluntary.
The official Xinhua news agency in November cited health authorities as saying 18.8 million people in the region had received such physicals in 2017 for a 100% coverage rate.