A TALIBAN suicide bomber who infiltrated Afghanistan’s defence headquarters in Kabul this week had travelled from London, investigators believe.

The Times has learnt that Britain’s intelligence services have been passed details of the militant who carried out Monday’s attack.

Senior sources in Afghanistan said that the failed bomber’s name and other personal details were forwarded to London, suggesting that he had been living in Britain.

The attacker, wearing a sergeant-major’s uniform, shot two guards after tricking his way into the building and was outside the office of Abdul Rahim Wardak, the Defence Minister, when he was shot by bodyguards before being able to detonate his suicide vest.

The Taliban said he was a “sleeper” who had served with the Afghan Army for many years. But investigators deny this, saying he was too young to have reached that rank, had long hair and was wearing new boots.

The Foreign and Commonwealth Office were unable to confirm the claim. If the attacker proves to have had British nationality it will be the first known case of a suicide bomber from the country travelling to Afghanistan. Suicide bombers from Britain have been killed in Israel, Kashmir and Somalia in recent years.

Although rejecting claims that he was a sleeper, both Afghan and Nato commanders acknowledge that he must have been acting within inside help.

A spate of killings by insurgents wearing the uniform of the Afghan National Security Forces over the past eight days had underlined the threat posed by turncoats, whether infiltrators or impersonators, according to Lieutenant-General William Caldwell, the three-star US general who heads Nato’s training mission in Afghanistan.

“It’s wake-up call for all of us. It’s the recognition one more time that there’s a continuous effort to penetrate, especially into the Afghan system.”

The general added that there was “no question” that the Taliban, denied freedom of movement by the troop surge had turned to suicide bombers as it chased headlines.

“They are now looking for other ways with a small investment on their part to try to gain a strategic impact. There could have been 30 engagements today in which 50 insurgents were killed but they won’t make the headlines. But one insurgent wearing a suicide vest and getting inside a military installation will.”

Keen to deny the Taliban a propaganda coup, Nato insists there is no evidence of any insurgent infiltrating the army or police with the aim of turning on other recruits or foreign soldiers.

There have been 20 attacks by militants wearing Afghan National Army or Afghan National Police uniforms in the past two years and the latest rash of so-called “green-on-blue” attacks brings the toll of coalition personnel killed in such incidents to 38.

Each further undermines the trust between foreign and local forces, vital to the strategy of handing over security to Afghan forces to enable a withdrawal.

Although the Taliban almost always claim an attack by a uniformed insurgent was the work of a “sleeper” agent, Nato insists half were carried out by insurgents wearing uniforms stolen to order or taken from casualties in the battlefield.

Investigations carried out into the other ten found psychological factors rather than Taliban involvement in the majority.

These ranged from stress caused by parental pressure to enter an unwanted marriage to offence taken by an Afghan soldier to comments made by his German partners. He killed three and wounded six more.

Nevertheless Nato is ramping up efforts to root out potential turncoats. At least one infiltrator has been caught trying to join the police in Adraskan, Herat. Under interrogation he admitted to having been sent from Pakistan by the Taliban.