China’s close watch over its Islamic minority is being extended abroad, as Muslims from some Chinese regions make the Hajj pilgrimage wearing state-issued tracking devices.

The state-run China Islamic Association published photos of Chinese Muslims at the Beijing airport departing for Mecca in Saudi Arabia in recent days wearing customized “smart cards” on blue lanyards around their necks. The devices, which include a GPS tracker and personal data, are designed to ensure the wearer’s safety, according to the association.