Porn-obsessed wankers are the main recruits from Britain for radical jihadists in Islamic State, Boris Johnson has said.
The mayor of London took stiff aim at Muslim fundamentalists in an interview with The Sun, dismissing them as "losers".
Citing an MI5 report into Muslim extremism, according to the paper, Johnson said: "If you look at all the psychological profiling about bombers, they typically will look at porn. They are literally w*****s. Severe onanists.
"They are tortured. They will be very badly adjusted in their relations with women, and that is a symptom of their feeling of being failure and that the world is against them.
"They are not making it with girls and so they turn to other forms of spiritual comfort - which of course is no comfort.
"They are just young men in desperate need of self-esteem who do not have a particular mission in life, who feel that they are losers and this thing makes them feel strong - like winners."
He added he felt efforts to tackle extremism should come from within Muslim communities but claimed clerics had not been "persuasive in the right way with these people".
More than 500 Britons are thought to have gone to Syria and Iraq to fight with IS, while a report this week found many Western women in IS were "desensitised" to violence carried out by the militants and encouraged it on social media.
It is not the first time Johnson has been outspoken on terrorism - on a recent visit to the Kurdish regional capital Irbil, he called on the Government to supply sophisticated weaponry to Kurdish peshmerga fighters battling IS terrorists.
But he suggested that ministers were nervous about doing so because they feared they could be used by the Kurds to establish their own separate state, independent of the Iraqi government in Baghdad.