Threatened: Twitter headquarters in Silicon V
Threatened: Twitter headquarters in Silicon VReuters

A Jerusalem-based cell of the Islamic State (also known as ISIS) has threatened to kill Twitter employees and target its offices if the social media site does not stop closing down ISIS accounts.

Al Musra Al Maqdisia (The Supporters Of Jerusalem), which pledged allegiance to ISIS in February, was among several Islamic State-linked groups and Twitter users to encourage "lone-wolves" to attack Twitter offices in retaliation for hampering jihadi PR efforts, and specifically threatened to "bring the war" the the company's central headquarters in San Francisco, the Vocative website reported.

Using the hashtag "#TheConceptOfLoneWolfAttacks", one tweet declared: "The time has arrived to respond to Twitter's management by directly attacking their employees and physically assassinating them!! Those who will carry this out are the sleepers cells of death."

Another read: "Twitter management should know that if they do not stop their campaign in the virtual world, we will bring the war to them in the real world on the ground."

Ironically, the account used to post the tweets has now been suspended by Twitter.

The Islamic State has utilized social media as part of a slick PR campaign that has seen it eclipse its rivals in Al Qaeda among young aspiring jihadis, particularly from the English-speaking world. By doing away with the need for old-fashioned jihadi internet forums - many of which can only be accessed by recognized members - the group has managed to spread its message, including gruesome images of executions and "martyred" fighters, further than any other Islamist group, and swelled its ranks of foreign fighters.

Twitter, for its part, has been playing a cat-and-mouse game with the plethora of ISIS-linked or supporting accounts, in an attempt to police its site for prohibited hate speech and incitement to violence. Although it has not succeeded in silencing ISIS's message, clearly the policy is at the very least hampering the group's Twitter "outreach" efforts enough to elicit such direct threats.

The issue has been a hot topic on ISIS-linked forums, with users sharing simple methods to get round the bans such as making minor changes to usernames and Twitter handles.

Currently, ISIS is not thought to have anything like the foreign network of terror cells maintained by Al Qaeda. However, the threat of so-called "lone wolf" attacks is still a very real one, security experts warn - illustrated by the deadly shooting at the Brussels Jewish Museum earlier this year, which was carried out by an ISIS member who returned from Syria.