Human Rights Watch says it has found new evidence that authorities in one of China's most repressive regions are sweeping up citizens' personal information in a stark example of how big-data technology can be used to police a population.

The rights group used publicly available government procurement documents, media reports and interviews to assemble details of the policing program, called the “Integrated Joint Operations Platform,” in Xinjiang, a sprawling area in northwest China that security officials say harbours separatist and religious extremist elements.

Unidentified sources inside Xinjiang described to Human Rights Watch the computer and mobile app interfaces of the IJOP software that tracks almost all citizens of the Turkic-speaking Muslim Uighur ethnic minority and stores detailed information, including their travel history, prayer habits, the number of books in their possession, and banking and health records.

Procurement notices show that the IJOP also deploys licence plate tracking and facial-recognition cameras to follow people in real time and provide “predictive warnings” about impending crime, Human Rights Watch said.

Although surveillance is pervasive in many countries, including the United States, and has the potential for abuse, the technology is being deployed far more broadly in Xinjiang, said Maya Wang, senior China researcher at Human Rights Watch and the report's author.

“In China the programs are very explicitly focused on people who are politically threatening or an entire Uighur ethnic group,” Wang said.

An official in the press office of Xinjiang police headquarters on Monday confirmed AP's questions had been received but said leaders were out and he had no idea when or if there would be a reply. The official, like many Chinese bureaucrats, declined to give his name because he wasn't authorised to speak to reporters.

China's 10 million Uighurs already face a raft of restrictions not imposed on people of the Han ethnicity, who are the overwhelming majority in China. Uighurs face multiple hurdles in procuring passports and those who have them are required to leave them with the police.

Hotels are required to register their presence with the local authorities and frequently turn them away to avoid the hassle. Frequent road blocks and checkpoints across the vast Xinjiang region enable authorities to stop people and check their mobile phones for content that might be deemed suspicious.

Such pressure was ratcheted up following a series of deadly attacks blamed on Uighur extremists seeking independence from Chinese rule.

A 2017 investigation by The Associated Press showed that thousands of Uighurs in Xinjiang, and possibly many more, have been sent to an extrajudicial network of political indoctrination centres for months at a time for reasons including studying abroad and communicating with relatives abroad.

The AP also found evidence in government documents and procurement contracts of the Xinjiang government, compiling biometric and personal data and systematically rating its Uighur citizens' political reliability.

The Human Rights Watch report reveals for the first time that the disparate data collection efforts appear to be unified under one central digital database that calculates citizens' political risk.

Use of the integrated computer system has led to people being detained and sent to political indoctrination centers, Wang said, citing interviewees who were kept anonymous out of concern for their safety.

Wang said she has found evidence that Chinese police are building similar big-data tracking capabilities in other parts of the country under a program called the “police cloud”, but do not deploy them to such an extent as in Xinjiang.