A subsidiary of China Electronics Technology Group announced in 2016 that it would start working with the Xinjiang government to combat extremism by collating data on the behaviour of citizens and flagging unusual activity to the authorities.

Some people targeted by the system have been detained or sent to "political education centres" as part of the region's security campaign, according to the HRW report, which cites official announcements and two unidentified sources who have seen the programme in operation.

"For the first time, we are able to demonstrate that the Chinese government's use of big data and predictive policing not only blatantly violates privacy rights but also enables officials to arbitrarily detain people," said Maya Wang, a Hong Kong-based researcher at HRW.

Responding to the report, a spokesman from the Xinjiang government referred Reuters to a government white paper on human rights in Xinjiang, and said not to "believe there is rain just because you hear wind," a phrase that means to worry or complain about something that does not exist.

Reuters was unable to independently verify HRW's claims. China's Ministry of Public Security did not respond to requests for comment.

A similar design of predictive security software is also being rolled out in other regions of China but surveillance is more intrusive in Xinjiang and there are fewer protections for suspects due to government concerns about unrest, she said.

Waves of violence have rocked Xinjiang in recent years, largely fuelled by tensions between the Han majority and the mostly Muslim Uighur minority who call the region home.

Wang said that, while it was unclear whether the system explicitly targeted Uighurs, forms to gather information for the programme asked about religious practice and overseas travel.

Official reports about the programme say it has helped police catch criminals guilty of petty theft and illegal financial dealings, as well as to find Uighur officials who are disloyal to the ruling Communist Party.

The "Integrated Joint Operations Platform" pushes lists of people of interest to the police for investigation by crunching data from CCTV cameras, ID card checks and WiFi connections of phones and computers, as well as health, banking and legal records.

These lists are meant to be acted upon by measures including face-to-face visits within a day, according to state media reports. The exact algorithm for weighting the various factors was unclear.