A British Muslim who claims to have helped recruit more than 200 British volunteers to fight for the Taliban today warned many would return home to launch terrorist attacks here.
Hassan Butt, 22, who was brought up in Manchester but is now based in Pakistan, said he would personally encourage attacks on political and military leaders and government buildings in Britain.
Although some volunteers had been "martyred" during the war in Afghanistan, he warned a "new phase" of terrorism would be launched on Britain and he would encourage the Muslims without any hesitation.
Mr Butt also claimed he had returned to Britain for three weeks since September 11 undetected by the security services.
He told BBC Radio 4's Today programme that many of the British volunteers were now in Pakistan "organising operations".
He added: "If they do return (to Britain) I do believe they will take military action within Britain.
"One thing I've always tried to stress the point is that the mujahedin that are coming in from Britain to strike at the heart of the enemy which is within its own country, within Britain ... I have always been in favour of this."
He said the targets would be "British military and government institutes, as well as British military and government individuals."
Mr Butt added: "The mere fact that the British Government had no idea I was here shows the incompetence and shows the vulnerability that Britain has when it comes to dealing with the mujahedin and the Muslims."
Dr Ghayasauddin Siddiqui, leader of the Muslim Parliament of Great Britain told
the Today programme: "It is a very worrying and frightening point of view.
"These young men have been guided or rather misguided by people of little understanding.
"The fact that they are using Islam as a cover for their evil designs is the most frightening part of this interview.
"I think it is more fantasy than realism, but I simply hope that these people, these young men, will realise their mistakes, mend their ways and re–order their priorities."
He added he hoped that the authorities in Pakistan would keep an eye on the men.
Shadow home secretary Oliver Letwin said: "We don't really know whether this chap is largely telling the truth or largely fantasising."
Mr Butt's claims that he had entered the country for three weeks had to be taken most seriously, he told the programme.
"If it is true then it tends to suggest that the measures which the Home Secretary has rightly taken to try to increase the level of our intelligence effort in this direction has not yet bitten sufficiently.
"I think what we need to hear from the Government is some more about the steps that are now going to be taken, how much money is going to be spent on it.
"I think it is becoming reasonably clear that the fact that our security effort was largely right and understandably focused on Northern Ireland has left us somewhat exposed in relation to a group of people who have different aims, different methods, different languages and so on.
"We clearly have some work to do yet to protect ourselves. There is a real threat here, I think we all agree about that, and we are not going to be able to protect ourselves against it unless we have adequate security."
Butt was reported to be in Britain last month, having returned from Pakistan.
The militant was said to have approached The Mirror with an attempt to sell the story of his experiences recruiting British Muslims for Osama bin Laden for £100,000.
The newspaper said it rejected his offer and reported his presence to Scotland Yard, but officers were quoted as saying he could not be arrested as he was not wanted for any offences in the UK.
He had travelled to Britain on his own passport and met Mirror representatives in central London, the paper said.Reuse content