So-called Islamic State group (IS) has shifted its propaganda distribution to the secure mobile messaging app Telegram from Twitter, where its accounts have been repeatedly shut down over the past year.

IS and other jihadist groups appear to be exploiting new functionality introduced by the app last month, which allows users to broadcast their messages to an unlimited number of members via their own Telegram "channel".

On 26 September, just four days after Telegram trumpeted the launch of its new "Channels" tool, IS media operatives on Twitter started advertising the group's own channel dubbed Nashir, which translates as "Distributor" in English.

It has already amassed more than 4,500 subscribers.

Since then, IS propaganda has started appearing first via Telegram, often several minutes before being posted to Twitter.

The group's claim for an attack on Saudi and Emirati forces at a hotel in the Yemeni city of Aden on Tuesday was posted first on Telegram, for example, although Twitter remains a key platform for IS to spread its message.

IS appears to be hoping the Berlin-based Telegram will offer it a more stable and resilient platform for its propaganda, faced with a sustained clampdown on its Twitter presence.

But Telegram itself suggests it will take down illegal material that is made publicly available via the app - including posts related to IS, according to its website.

IS has not had an official presence on Twitter since July 2014, when its last branded accounts were shut down.

It then experimented with a series of less well-known social media platforms, such as the privacy-focused Diaspora as well as VKontakte, Russia's largest social network, whose co-founders the Durov brothers went on to set up Telegram in 2013.

But IS was soon kicked off those platforms too.

Since then, Twitter has remained the group's preferred platform. But it has been caught up in a cat-and-mouse game with the Twitter administration, which has also led to its quasi-official, non-branded accounts routinely suspended.

Even before IS launched its latest propaganda channel via Telegram, there had been evidence that the group and its members were using the app.

Earlier in September, IS had advertised an Iraqi mobile phone number, which people could use to get in touch with the group via the Telegram app in order to pay a ransom for two hostages being held by the group.

And jihadists inspired by IS, including a British teenager convicted recently, have used the app's secure encrypted messaging to conduct attack planning.

Jihadists have been drawn by Telegram's boast to provide a "secret chat" facility, which heavily encrypts messages user-to-user with a unique key to avoid interception by hackers or government agencies.

Telegram is so confident of its security that it twice offered a $300,000 reward to the first person who could crack its encryption.

But it is the app's new public broadcast function that jihadists have been quick to latch on to and it is not just IS that has started exploiting it.

Al-Qaeda's Yemen branch (AQAP) launched its own Telegram "channel" on 25 September, although its material is still coming out first via Twitter, where the group has its own official accounts. And the Libyan Ansar al-Shari'ah group created its channel the following day.

A raft of other pro-IS and pro-al-Qaeda media groups have also set up shop there.

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