Chinese police have reportedly set up checkpoints to ensure that ethnic minorities in the western Xinjiang province have downloaded state-mandated spyware to their mobile devices.
The surveillance app, known as Jingwang, is said to search the device for files that match those blacklisted by the authorities for terror-related content.
It can also prevent the spread of certain content via social media and online chat platforms and block access to illegal and malicious sites, according to reports.
The new rules are only in place in Xinjiang, which has a large population of Uyghur Muslims and a history of social unrest.
After large-scale rioting in 2009, for example, Beijing is said to have blocked internet access completely in the region.
This move is the latest to crack down on separatist terrorist activity in the province frequently inspired by jihadism.
Users in Xinjiang were apparently told on 10 July that they had 10 days to download and install Jingwang. If they are now stopped at a checkpoint and found to have failed to do so, they risk being detained by police for up to 10 days.
Some have already been arrested, including a group of Kazakh women whose WeChat conversations were monitored via the app and deemed illegal, according to Radio Free Asia.
This is merely the latest crackdown by the Chinese authorities on internet freedom, following a Ministry of Industry and Information Technology move in January to make all non-government approved VPNs illegal.
In June, the Xinjiang authorities instructed all citizens and business owners to submit their ID cards, mobile phones, external drives, laptops, and any media storage to local police for “registration and scanning” by 1 August.
That said, the UK last year introduced the most intrusive state surveillance laws of any western democracy with its Investigatory Powers Act, using anti-terror rhetoric to force it through parliament.