By Michael Holden and Kate Kelland
LONDON (Reuters) - Peer pressure from radicalised fighters in Syria and Iraq is more influential in attracting new recruits from Europe than Islamic State (IS) propaganda, according to British experts.
The International Centre for the Study of Radicalisation and Political Violence (ICSR), in a study to be released next month, found that peer groups and kinships were crucial in luring young fighters, rather than IS videos and Internet messages.
"When you look at what actually made them go...being angry is one thing, but actually packing your bags and going, it was always the friends that prompted that decision, never any piece of video on the Internet," ICSR's director Peter Neumann told Reuters at a conference on radicalisation in London.
Separate research presented at the conference by Kamaldeep Bhui, a cultural psychiatrist from Queen Mary University of London, found that the British Muslims most vulnerable to radicalisation were more likely to be young, depressed and relatively socially isolated, although not "loners".
Neumann said foreign fighters also use peer pressure to urge friends who can't get to Syria to carry out attacks at home.
European governments' desire to stop their citizens going to fight as insurgents in Syria has been galvanised by the killing of 17 people by Islamists in Paris two weeks ago, with discussions looking at how to curb radical Islam on the Internet.
Neumann said there was a mistaken assumption that online propaganda was the biggest influence.
The ICSR, which has collated a database of some 700 European fighters in the last two years, analysed 10 British fighters and reconstructed their paths to radicalisation using detailed data from their social media histories.
It found that close-knit friendships and a sense of obligation were the predominant reason for joining a foreign conflict, underlying why European recruits appeared to come in "clusters".
Neumann said Syrian foreign fighters' social media use also showed the most influential people were not IS officials, but "cheerleaders" for the cause, often not based in Syria or Iraq. The two most important Islamic voices identified were an American, Abu Musa Jibril, and Musa Cerantino, based in Australia.
He said he had seen examples, especially among women who had gone to Syria, of pressure on would-be fighters to do something in their homeland.
"We've seen that anecdotally, I'm not sure how widespread that is," he said. "Certainly there have been messages and tweets ... basically telling people to stay where they are and do something there."
(Editing by Angus MacSwan)