China is closely monitoring 2.5 million people in what has been called a "Muslim tracker", exposing millions of records containing sensitive personal information on an unprotected online database, according to a Dutch cyber expert.

Key points: The database was unprotected online for almost seven months

The database was unprotected online for almost seven months Many names appear to be typically Muslim and located in Xinjiang province

Many names appear to be typically Muslim and located in Xinjiang province Experts say it reveals China's widespread surveillance of the Uyghur minority group

Victor Gevers, a researcher with GDI.foundation, found names, identification card numbers, birth dates, employers and locations were all exposed for almost seven months on an insecure database run by SenseNets, a company contracted by Chinese police that uses artificial intelligence for facial recognition, crowd analysis and personal verification.

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"This insecure face recognition/personal verification solution is built and operated for only one goal," he wrote on Twitter.

"It's a 'Muslim tracker' funded by Chinese authorities in the province of Xinjiang to keep track of Uyghur Muslims."

"It looked like that because most of the coordinates were pinpointing to a known region where these people are living in camps."

An estimated 1 million Uyghurs have been allegedly detained in what China calls "vocational centres" but what many critics have called internment camps in the western province of Xinjiang.

Mr Gevers said he took a sample of around 1,000 records of names written in Chinese characters that, once translated, appeared to be traditionally Muslim names not Han Chinese.

Locations were recorded by trackers they passed — usually cameras in fixed positions that provide a video feed for facial recognition.

The database is now protected — after being re-opened for a 50-minute window — but Mr Gevers said it was not uncommon for sensitive information on Chinese databases to be freely available on the internet.

China's Ministry of Foreign Affairs has been contacted for comment but did not reply at the time of publish, but late last year Foreign Minister Wang Yi controversially told the global community to ignore the "gossip" about Xinjiang province and support the country's efforts to fight Muslim terrorists.

"[People] should not listen to gossip or rumour, because the Xinjiang regional government, of course, understands the situation in Xinjiang best, and not some other people or organisations," Mr Wang said.

"The efforts are completely in line with the direction the international community has taken to combat terrorism, and are an important part of the global fight against terrorism."

'Astonishing scale of surveillance'

Sorry, this video has expired Surveillance software identifies details about people and vehicles in Beijing.(Photo: Reuters/Thomas Peter)

Fergus Ryan, an analyst and China expert at the Australian Strategic Policy Institute (ASPI), said that the technology had been deployed as "part of Beijing's repression of the Uyghurs, Kazakhs, and other ethnic minorities" and that Xinjiang was "a major testing ground for these types of surveillance technologies".

"It helps to build a picture of the astonishing scale of surveillance of these minorities," he said.

"The trackers were reportedly located at or near mosques, hotels, police stations, internet cafes and restaurants, and that database included details of 2,565,724 people."

An ABC investigation using ASPI research and satellite imagery documented the expansion of 28 detention camps that are part of a massive program of subjugation of Xinjiang's Muslim population.

Three Australians were detained and released from the political re-education camps, Australia's Department of Foreign Affairs and Trade (DFAT) revealed in October last year.

An estimated 17 other Uyghurs with strong ties to Australia, either through permanent residency or spousal visas, are believed to be detained in China's crackdown on Muslim minorities, according to a report from the Guardian last week.

"Given the scope of that surveillance, it's quite possible the 17 Uyghurs who are Australian permanent residents/spouses were captured in the data," Mr Ryan said.

DFAT last week told the ABC it was not aware of any Australian citizens currently being detained in Xinjiang, but it was "aware of a number of cases where family and friends in Australia are unable to contact individuals who have travelled to Xinjiang".

The Government has been making enquires with Chinese authorities about the whereabouts of these people when Australian family members had requested help.

Mr Ryan said access to the data should be given to trusted NGOs and think tanks to document and add to the existing evidence of human rights violations.

"This case shows that China's cyber surveillance is vast and it's growing," he said.

"It also shows that this technology is being deployed in violation of a number of other fundamental human rights principles, such as the right to privacy."