The militant group Islamic State (Isis) has warned followers to avoid using popular internet-based communications apps like WhatsApp and Telegram amid fears they enable the US-led coalition to pinpoint their positions.
Around 20 senior IS commanders have been killed in Iraq and Syria throughout 2016, including some of the group's most senior leaders.
The decree came via an article in the militant group's weekly online magazine, al-Naba. "If you get onto the programmes like WhatsApp and Telegram or others from Mosul, and get in touch with a person being tracked, the crusaders will start thinking about you," it reads, "assessing your importance and identifying the locations of the (Islamic State) centres by following you."
The article warns that any militant who uses a mobile phone is putting themselves and others at risk. "Switch off your phone after you finish your communication and beware of the greatest disobedience of all - switching it on when your are in one of the offices," the piece continues. "As long as it has power, the phone is spying on you."
Isis has cut back on Twitter use in recent years and instead favoured a range of other messaging apps, of which WhatsApp and Telegram have been the most popular.
The Paris attacks of 2015, in which 130 people died, were in part coordinated from the Middle East using the apps. Now pro-Isis channels on Telegram are warned not to attempt to disseminate propaganda and use the service simply for communication, according to Reuters.
In Mosul, where Isis is surrounded and cut off from other areas it occupies, the group has executed residents for having mobile phones and even SIM cards. Satellite dishes have also been confiscated to prevent locals finding out about the progress of the Iraq army in the battle for the city.
Isis is also reported to have shot residents who refuse to allow its fighters into their homes. An official from the International Committee of the Red Cross told Reuters the battle for Mosul could still take months due to the fierce resistance allied forces continue to face.