The enemy within

Six more arrests as security services warn there could be more British suicide bombers

British security agencies are facing a nightmarish new threat in the wake of last week's suicide bombing in Israel by two British Muslims. Sources close to MI5 and Special Branch admit that the pair were unknown to both agencies. Nor do they know how many other disaffected British Muslims might be prepared to stage similar attacks.

Asif Mohammed Hanif, from Hounslow, west London, blew himself up in a Tel Aviv café early on Wednesday morning, killing three other people and injuring 35. Omar Khan Sharif, from Derby, is on the run in Israel after his hidden explosives failed to detonate. The fear is that if they had chosen a target in Britain, they would have gone undetected.

Anti-terrorist police were last night questioning six people arrested in Derbyshire, Nottinghamshire and London in connection with the Israel bombing. The three men and three women were being held at the high-security Paddington Green police station in central London, on suspicion of helping to plan terrorist attacks. Security sources say the investigation is highly sensitive and "extremely important".

"A spate of individual fanatics, each committing an act of horrendous terrorism, is what senior MI5 officers lie in bed sweating about at night," said one former intelligence officer. "These are the most difficult people to spot, especially if they are British-born."

A Whitehall source said: "What we cannot be complacent about is the possibility of previously unknown individuals acting on their own, perhaps inspired by the Iraq war or [Osama] bin Laden and the events of 11 September."

Last week's attack was unique in several respects. It was the first suicide bombing by a Briton, the first by a foreigner in Israel and the first perpetrated by bombers travelling into Israel from Gaza after 89 previous attacks from the West Bank. All three factors minimised the chances of the attackers being intercepted before they carried out their mission.

Before the 2001 attacks on New York and Washington, carried out by terrorists whose activities had passed virtually unnoticed by American intelligence agencies, MI5 was confident that it had rounded up all the active al-Qa'ida terrorists in Britain. Some have been extradited and others are in custody in Belmarsh prison, south-east London.

Since 11 September 2001, MI5 has closely monitored about 30 people – most of North African origin – whom they suspect of close links with al-Qa'ida. They are ringed by supporters and active sympathisers, believed to number between 300 and 600.

But Hanif and Sharif carried out their attack on behalf of Hamas, a Palestinian nationalist group which does not share al-Qa'ida's vision of world Islamic dominance. Nor is Hamas known to recruit non-Palestinians, though Israel's success in suppressing local suicide bombers may have led the group to change its policy.

It appears, however, that the two Britons sought out Hamas. This raises the spectre of a generation of young British Muslim men who have become more susceptible to targeting by extremists. The atmosphere, heightened by the September 2001 attacks and America's response in Afghanistan and Iraq, has also been made more tense at home by campaigns against immigration and asylum-seekers, as well as gains by the far-right British National Party in last week's local elections.

In Sharif's home town of Derby, Omar Abdullah, a spokesman for the radical Islamist group Al-Muhajiroun, whose meetings the bomber was known to have attended, said: "You look at everything that's happened in the world in recent times, and of course there are going to be Muslims who are prepared to carry out attacks like this. British men go off to join the Israeli army, and when they die nobody makes anything of it. The only difference is that the Israelis wear a uniform."

Although Al-Muhajiroun preaches global jihad and has refused to condemn suicide bombings, Mr Abdullah insisted that his organisation did not promote or condone violence.

Many in Derby did not believe the discovery of Sharif's passport after the bombing was proof of his guilt. "All we have is the word of one Israeli police officer," a young Muslim man said. "The passport could be a forgery."

But another resident disagreed, saying: "I can understand exactly why a young Muslim man would want to do what this man is supposed to have done. In fact I'm surprised it hasn't happened more. The American world order is totally unacceptable – it's the haves decreeing how the have-nots should live."

Although Sharif received a secular school education before going on to Kingston University in London, a local Muslim said that is what might have opened his eyes.

"Take an ordinary impoverished Muslim, and he might be prepared to accept that that is what Allah has decided for him," he said. "You see things differently once you have learnt more."

MI5 has spent years seeking to develop strategies for identifying people who have no record of extremist behaviour before they become terrorists. Since September 2001 the agency has nipped a number of planned terrorist attacks in the bud.

But the Israel bombers are different. "How can the intelligence services monitor these kind of people in a democracy?" asked the Whitehall source. "We don't have mind control. MI5 are reliant on the person telling someone else, and that we are told about that communication. And how do you distinguish between those who talk about doing something and those prepared to act?"

Although Hanif and Sharif were taught by the British-based cleric Omar Bakri Mohammed, the self-styled "emir" of Al-Muhajiroun, terrorism experts do not believe they were recruited in Britain. "It is interesting that both men went to university in Damascus," said Magnus Ranstorp, deputy director of the Institute for the Study of Terrorism at St Andrews University.

"I suspect that was where they were identified by Hamas, which then exploited their idealism. They would have been talent spotted and then groomed.

"There is a growth in the number of disaffected Muslim youth in Britain, and they will be exploited.

"There have been radical clerics calling for the mujahedin to strike at Israel ... and we are seeing a new kind of person becoming involved with the Palestinian cause."

Dr Ranstorp said the attack reflected "a worrying change of tactics" by Hamas, since it was the first time it had used foreigners, and believed that Hamas has been taking lessons from Lebanese Hizbollah in recruiting from Europe. "Hizbollah have been using foreigners and disguising their own agents as foreigners since at least 1996," he said.

"Shin Beth [the Israeli internal security service] knows the address of just about every Hamas leader and operative in the West Bank and Gaza Strip. After months of suicide attacks against Israeli targets it is almost impossible to smuggle explosives into Israel."

The suspects' British passports would have enabled them to travel into Israel from Gaza hours before the bombing. The Gaza Strip is fenced and tightly policed and no previous bombing has been mounted from the territory in the 31 months of the Palestinian uprising.

"I think that the intent was to undermine the US-supported 'road-map' peace plan and also to frighten tourists to Israel, doing more economic damage," said Dr Ranstorp.