The Chinese government has curbed freedoms in the province for the local Muslim population, installing facial recognition cameras on streets and in mosques and reportedly forcing residents to download software that searches their phones.
An investigation by the Guardian and international partners has found that travellers are being targeted when they attempt to enter the region from neighbouring Kyrgyzstan.
Border guards are taking their phones and secretly installing an app that extracts emails, texts and contacts, as well as information about the handset itself.
Tourists say they have not been warned by authorities in advance or told about what the software is looking for, or that their information is being taken.
The investigation, with partners including Suddeutsche Zeitung and the New York Times, has found that people using the remote Irkeshtam border crossing into the country are routinely having their phones screened by guards.