The arrests of 24 suspects, mostly British Muslims, allegedly planning to launch a spectacular suicide attack even more lethal than 9/11, has sent shock waves around the world. The supposed plotters are British-born men and women, between the ages of 17 and 35. How could such seemingly normal people, many with jobs, families and an education, become radicalised to the extent that they were prepared to die in order to kill thousands of innocent civilians?

An open letter to the Prime Minister from three of the four Muslim MPs, three of the four Muslim peers, and 38 Muslim organisations including the Muslim Council of Britain and the Muslim Association of Britain blames government foreign policy. Although Downing Street is dismayed by the letter, the thrust of its argument was acknowledged by a Home Office report last year, several days after the 7 July atrocities, which admitted that young British Muslims were particularly disillusioned by "a perceived 'double standard' in the foreign policy of Western governments". The report says that "a sense of helplessness" about this situation is exacerbated by the "lack of any tangible 'pressure valves', in order to vent frustrations, anger or dissent".

British intelligence agencies are acutely aware of this connection. In February 2003, the Joint Intelligence Committee warned the Prime Minister that the al-Qa'ida threat would be "heightened by military action against Iraq". Just over two weeks before the 7/7 attacks in London last year, the Joint Terrorism Analysis Centre noted that the Iraq issue provided a "motivation and a focus" for UK-based terrorist activity.

Yet, while many British Muslims oppose the occupation of Iraq, they are hardly unusual in this regard. Millions in Britain oppose our government's foreign policy. There is therefore something deeply unsatisfactory about this explanation -- clearly, grievances over the war must be accounted for, but what remains mysterious is how such grievances are converted into the planning of suicide atrocities.

Nothing obviously distinguishes British Muslim terror suspects. They don't appear to suffer from obvious forms of social exclusion. However, many of them seem to have been looking for something more in life. Neighbours and friends have described them as non-descript, well-behaved practising Muslims. Several were new converts to Islam.

The most recent arrests apart, there are perhaps 3,000 Muslims in this country who are, or have been, involved in al-Qa'ida-related terrorist activity. The vast bulk of these were recruited after 9/11 during the war in Afghanistan, by a small group of foreign Islamist preachers and activists revolving around the Finsbury Park mosque in north London. They include Omar Bakri Mohammed, Abu Hamza, Abu Qatada, Abu Izzadeen, Mohammed al-Massari, Saad al-Fagih, among others. Out of these, only Hamza and Qatada are in custody. Bakri is in exile.

The brand of Islam promoted by Bakri, Izzadeen and others is a highly charged political ideology that feeds in part on Muslim grievances about Western foreign policy. Legitimate concerns are turned into a paranoid psychology of victimisation that views a monolithic "West" as hell-bent on the destruction of Islam.

What Western military jargon calls "collateral damage", wrought by interventions in Iraq, Afghanistan, Lebanon and elsewhere, becomes fodder to propagate a dualistic worldview in which the West is at perpetual war with Islam. Hypnotic audio-visual techniques splice images of gruesome atrocities against Muslim civilians with those of al-Qa'ida leaders preaching justice. The resulting sense of victimisation is used to argue that a return to a global Islamist theocracy established through "jihad" is necessary to protect Muslims from oppression. The sense of helplessness, frustration and anger is filtered into a cult- like ideology of death as a path to hope.

In methods and goals, this extremist vision is not significantly different from other dangerous cults that prey on impressionable minds, except in terms of the massive scale of its material support network. The letter from Muslim leaders in Britain ignores the fact that this network is actively exported by Pakistan, Saudi Arabia and other Gulf states, as well as by groups such as the Muslim Brotherhood. They pour millions of pounds into mosques, organisations and charities in the UK, the United States, Western Europe and beyond.

The process of radicalisation is an expensive one. Saudi financing of al-Qa'ida through charities and foundations is well-known to the international intelligence community. Operatives such as Bakri and Hamza received lavish funding from this network.

The British government's response to the networks spearheading this radicalisation process has been ambivalent. Over the past decade, close economic ties to repressive regimes such as Saudi Arabia have led Western leaders to turn a blind eye not only to human rights abuses there, but also to the sponsorship of terrorist networks and a corresponding extremist ideology of Islam.

Simultaneously, the Government has failed to arrest, charge or prosecute some of the most senior Islamist operatives linked to terrorist activity. Now based in the Lebanon, Omar Bakri, for instance, continues to oversee the radicalisation of hundreds of British Muslims via the internet , encouraging them to engage in terrorism.

The authorities must take legal action against Islamist preachers who lead these networks. Both the Government and media should stop treating extremist organisations as fit representatives of mainstream Muslim opinion. And all of us must be clear that extremist Islam is a well-funded and sophisticated lie, much like the Western imperialism it purports to resist.

Nafeez Mosaddeq Ahmed is the author of 'The London Bombings: An Independent Inquiry'. He teaches international relations at the University of Sussex