Abu Muntasir, a former radical Islamist preacher who once enjoyed a large following in Britain, sobs uncontrollably as he recalls the moment he decided to turn his back on extremism.

Charting the involvement of foreign jihadis in previous conflicts from Afghanistan to Bosnia and Chechnya, the film also features the stories of other British Muslims, who, like Abu Muntasir, eventually renounced extremism.

More than 500 women from Western countries have also left to join ISIS, according to research last month by the Institute for Strategic Dialogue and the International Centre for the Study of Radicalization at King's College, London.

One British woman interviewed in "Jihad" said she joined an extremist group after being sexually abused.

In another interview, a former follower of Abu Muntasir described being subjected to racist taunts growing up.

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