Western governments have overstated the role the Internet plays in the recruitment of militants, and measures to block extremist material are crude, expensive and counterproductive, a report said on Tuesday.
Any attempts to filter or restrict access to sites grooming potential suicide bombers would be impractical and ineffective, said the study by the International Center for the Study of Radicalization and Political Violence (ICSR) in London.
In fact there was little politicians could do, said the report, which brought together government, industry and experts to look at the issue.
Self-radicalization and self-recruitment via the Internet with little or no relation to the outside world rarely happens, and there is no reason to suppose that this situation will change in the near future, it said. Indeed it is largely ineffective at drawing in new recruits.
For years, governments and security agencies have warned that the Web was allowing extremists, particularly Islamist militants, to recruit and radicalize people to their causes.
Former U.S. Homeland Security Secretary Michael Chertoff once said recruits no longer needed to travel to al Qaeda camps overseas, and the European Commission has suggested trying to block online searches for material such as bomb-making recipes.
Last week a report found extremist groups in Southeast Asia were increasingly using the Web to radicalize youths.
However, the study suggested fears about the radicalizing power of the Internet appeared misplaced. Peter Neumann, head of the ICSR, said there had been only four or five reported cases across Europe where the process had taken place wholly online.
He told Reuters that Internet Service Providers could do more to deal with users' complaints about extremist material, and governments would regulate if the ISPs failed to bring in a system to better police content.
But it was a fallacy that there is some sort of switch that can be pressed and you can eliminate all extremist radicalizing content from the Internet.
Officials have argued that it should be possible to filter militant material in the same way authorities crack down on child pornography.
But the report said this analogy was flawed: issues surrounding militant content are less clear cut, and it is politically hard to decide what is illegal and what is merely offensive.
Removed websites can soon crop up again using a different Internet Service Provider (ISP); filtering methods are either too crude (because they block legitimate sites), too expensive (as they need constant updating), or they impede Internet traffic.
Meanwhile almost nothing can be done to target chat rooms, and networking sites, the report said,
While most of the focus has been on al Qaeda-inspired Islamist militants, far-right white supremacist sites are equally as popular, the report found.
(Editing by Mark Trevelyan)