Two bombers 'known to MI5'

Two of the four suicide bombers who killed 52 people in the July 7 attacks were scrutinised by MI5 last year but were not considered to be a threat to national security, the Independent has discovered.

Shahzad Tanweer, 22, who detonated a rucksack bomb on the Tube at Aldgate, east London, is believed to be the second of the terrorist gang to have been indirectly linked to an alleged plot to build a bomb in 2004. It had already been established that suspected mastermind Mohammad Sidique Khan, 30, had been known to the intelligence services.

The disclosure that a second of the four bombers had come to the attention of MI5 is likely to increase pressure for a public inquiry into the London attacks and any failures in intelligence.

Charles Clarke, the Home Secretary, is resisting calls for an independent inquiry.

The newspaper has also established that there are so many new terrorist suspects coming to the attention of security agencies that there are not enough officers to carry out all the investigations.

Tanweer, who killed eight people, including himself, is believed to have been the subject of a routine assessment by MI5. It was decided he was on the periphery and no further action took place.

The decision by MI5 to disregard two of the men who would later become suicide bombers was based on the assessment that they were not on the intelligence "radar" and only had an indirect link - via an associate of the gang under investigation - to the main targets.

But the disclosure highlights police and security services' lack of intelligence on a growing number of British-born Muslims who have become radicalised.

In the aftermath of the July 7 suicide bombings, it was thought that the terrorists had no known links to terrorism. But it later emerged that Khan, a teaching assistant from Dewsbury, Yorkshire, who killed six other passengers when he blew himself up on the Tube at Edgware Road, was the subject of a routine threat assessment by MI5 officers after his name cropped up during an investigation in 2004. Until now, Tanweer, from Beeston, Leeds, was not thought to have been looked at by security chiefs.

But more evidence has emerged of his previous involvement with extremists and it is thought that Tanweer and Khan could have had terrorist training in religious schools in Pakistan.

Meanwhile, sources have confirmed that some terror suspects, whom counter-terrorist officers would like to put under surveillance, are not being scrutinised because of a lack of resources.

Intelligence on an unprecedented number of British-based al-Qa'ida suspects is being uncovered.

Security and police officers have foiled three alleged terror plots in the past five months, but there is a growing belief within MI6, MI5 and Scotland Yard that a "successful" attack in Britain is inevitable in the coming year.

- INDEPENDENT