LONDON (Reuters) - From behind a computer keyboard at his London home, student Younes Tsouli used the Internet to spread al Qaeda propaganda, recruit suicide bombers and promote Web sites that encouraged the killing of non-Muslims.
The Moroccan-born student and two accomplices, one of whom he had never met in person, went on to become the first to be jailed in Britain for inciting terrorism over the Internet.
In September, a Scottish student described as a "wannabe suicide bomber" was imprisoned for eight years for owning terrorism material and distributing it via Web sites.
The two cases are examples of what Western authorities believe is the dangerous and growing role the Internet plays in spreading extremist propaganda and recruiting sympathizers to Islamist militant causes.
But can the West censor radical Web sites and, indeed, is it morally right to do so?
The perceived threat has prompted much talk from governments of the need for action. On Tuesday, the European Commission urged the EU's 27 states to crack down on militant sites.
"The Internet serves ... as one of the principal boosters of the processes of radicalization and recruitment and also serves as a source of information on terrorist means and methods, thus functioning as a virtual training camp," the Commission's proposal said.
New York's police chief described the Internet as "the new Afghanistan" in August. That echoed the views of U.S. Homeland Security Secretary Michael Chertoff, who said last year potential recruits no longer needed to travel to al Qaeda camps.
"They can train themselves over the Internet," he said.
However, many governments disagree about what should actually be done and experts express serious doubts about what would be effective, saying little research has been carried out.
Johnny Ryan, Senior Researcher at Dublin's Institute of International and European Affairs, said users could easily circumvent any restrictions imposed by the authorities.
"A workable Internet censorship system, even if one were desirable, is not possible within the EU, or anywhere else in the world with a comparable infrastructure or legal norms," he told Reuters.
Web sites could relocate from one country to another unless there was international agreement, while the controversial content was often distributed through services that are hard to block, such as legitimate chat rooms.
"In China, where censorship is a more serious business, users have developed a series of tools to break through government Internet blocks," said Ryan, author of the book "Countering Militant Islamist radicalization on the Internet".
Dr Akil Awan, of the Royal Holloway, University of London, another of the few academics to have studied the issue, agrees.
"The virtual jihadists are very net-savvy and generally are always two steps ahead of the authorities," he told Reuters, adding it would be morally questionable to censor jihadist Web sites that presented an alternative world view.
"These accounts may be skewed, tendentious and indoctrinating, but then so is a lot of other material on the Internet," he said.
Radical preacher Omar Bakri Mohammed, banned from Britain after the government ruled that he was not "conducive to the public good" in the aftermath of the July 2005 London bombings, said banning radical sites would be counter-productive.
Syrian-born Bakri, who has been named at several British terrorism trials as a leading influence on young militants, said it would be seen as part of a campaign against Islam.
"I don't think what they are doing is going to stop the Islamists or the Muslims from conveying the Islamic message," Bakri told Reuters by phone from his home in Lebanon.
"They should open debate, discussions, dialogue with the Islamists. There is no need to censor. If you think it is bad, why do you not debate it and destroy it in national media?"
Despite his exile, Bakri, who gained notoriety by calling the September 11 hijackers the "Magnificent 19", has continued to communicate with followers in Britain via Internet chat rooms.
"I don't preach much on the Internet like before. But I know very well Muslims worldwide are succeeding in using ... the Internet and I think they are doing very well," he said.
A simple search of the Internet shows how easy it is to find material that could concern the authorities, from speeches by Osama bin Laden and al Qaeda leaders to inflammatory videos.
Reuters found a blog supposedly used by prisoners in London's Belmarsh top security jail, including those convicted of soliciting murder at protests in February 2006 outside the Danish Embassy in the British capital.
"This blog is dedicated to those Muslim activists who have been held captive for various reasons -- many of them for demonstrating against the Danish cartoons depicting the Messenger Mohammad," said the blog.
However, it is also not clear whether messages, videos or sermons on the Internet alone can radicalize individuals.
"It is only the means through which individuals can become aligned with jihadist ideologies and causes. Other factors are equally important," the Royal Holloway's Awan said, adding it is estimated there are more than 5,000 extremist Web sites.
Meetings with committed jihadists in the flesh remains an important factor and Awan said even cases of apparent "self-radicalization" via the Internet quickly became conventional when plots were actually planned.
"It is also clear that militant Islamists dedicate significant resources to getting their message out online," Ryan said. "It is, of course, virtually impossible to determine the extent to which one is more important than the other."