Hong Kong (CNN) China's far-reaching security network is targeting tourists, with border guards secretly installing a surveillance app onto the phones of visitors to Xinjiang, according to a joint report by several major international media organizations.

If true, it would be the latest move to tighten surveillance in the heavily-repressed region, where the US State Department has estimated up to two million Muslim-majority Uyghurs are being held in detention camps.

There is a heavy police presence across Xinjiang and security cameras there are a common sight. From 2017, the Chinese government began to collect DNA and biometric data from millions of local residents.

The new joint investigation by organizations, including the Guardian and the New York Times, alleges the crackdown is now affecting visitors and tourists to the region. CNN has not been able to independently verify the report.

The Jieleixi No.13 village mosque in Yangisar, south of Kashgar, in China's western Xinjiang region on June 4, with a banner saying "Love party, love country."

Asked about the app Wednesday, the Chinese Ministry of Foreign Affairs said they had "never heard of (it)." CNN has sent a request for comment to the Xinjiang regional government but had not heard back at the time of publishing.

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