MI5 head warns of up to 30 terror plots at work in Britain

There are up to 30 alleged "mass casualty" terror plots in operation in Britain, as well as hundreds of young British Muslims on a path to radicalisation, the head of MI5 has said.

In an unprecedented public announcement yesterday, the MI5 director general, Dame Eliza Manningham-Buller, revealed that the caseload of the Security Services had risen by 80 per cent since January, and that the counter-terrorism agency was fighting to keep the rapidly growing threat under control

Describing the scale of the home-grown terrorist problem, she said MI5 and the police were tackling 200 groups or networks totalling more than 1,600 identified individuals in the UK who were "actively engaged in plotting or facilitating terrorist acts".

Islamic militants linked to al -Qa'ida were recruiting teenagers to carry out attacks using chemicals, bacteriological agents, radioactive materials and even nuclear technology.

Speaking to an audience at the department of contemporary British History at Queen Mary College in London, Dame Manningham-Buller said she was not seeking to be alarmist, and did not wish to stir up fear.

But she added that because of the sheer scale of what MI5 faces, the issue is a daunting one. "We shan't always make the right choices and we recognise that we shall have 'scare sympathy' if we are unable to prevent one of our targets committing an atrocity," she said.

The nature of the threat was increasing because of the radicalisation of British Muslims, she told the audience, including some as young as 16, and it "will be with us for a generation".

The young age of potential terrorists also made it difficult for MI5 to infiltrate the groups. "Young teenagers are being groomed to be suicide bombers," she said. "We are aware of numerous plots to kill people and to damage our economy. What do I mean by numerous? Give 10? No, nearer 30 that we know of."

At the extreme end, there were resilient networks directed by al-Qa'ida in Pakistan or some more loosely inspired by it, who were planning the attacks, she said. And while the training and the guidance comes from al -Qa'ida, it was "largely British foot soldiers here on an extensive and growing scale".

Given the scale of radicalisation, this indoctrination was happening to some while still at school, she said, adding: "If the opinion polls conducted in the UK since July are only broadly accurate, over 100,000 of our citizens consider that the July bomb attacks in London were justified."