The al-Qa'ida aide, who attended a "terror summit" in the tribal areas of Pakistan last year, told investigators in America that he recognised Mohammed Sidique Khan, the 30-year-old who triggered a bomb at Edgware Road station. Mohammed Junaid Babar, 29, is reported to have picked out Khan after being shown photographs of the four suicide bombers who killed at least 55 people in the 7 July outrage.
Babar, a Pakistani-American computer expert, was arrested on his return to the US from the al-Qa'ida summit in Waziristan. He has admitted a string of charges, including helping a foiled plot to bomb restaurants, pubs and railway stations in Britain, and has subsequently provided authorities with valuable information about the worldwide terrorist network.
Khan, a teaching assistant from Dewsbury, West Yorkshire, is known to have had links with an individual who came to police attention during an anti-terrorist operation in March last year. Germaine Lindsay, another of the London bombers, is reported to have had links with terror suspects in New Jersey and to be on a US "watch list".
The connections undermine claims that the bombers were "clean skins" - recruits with no previous links to terrorism - and will lead to renewed calls for an official inquiry into apparent intelligence failures. Police and security agencies are at loggerheads over claims that an al-Qa'ida suspect who could have masterminded the attack, and who entered Britain two weeks before the bombings, was not followed. Senior detectives insisted they would not be distracted from what they believe is a race against time to prevent a second attack.
Scotland Yard last night released the first picture from CCTV cameras showing all four terrorists together. Taken at 7.21am, it shows the bombers entering Luton station, from where they travelled to King's Cross in London. Deputy Assistant Commissioner Peter Clarke, head of the Anti-Terrorist Branch, said: "We still need to find out more about these four men and their movementson the morning of the bombings, and in the days and weeks before.
"Did you see these four men together travelling between Luton and King's Cross on 7 July? Did you see these four men together in the days before the attack? I would like to appeal to anyone who may have information that could prove useful to contact us. Do you have information on any of these four men?"
The worldwide hunt is also focusing on Pakistan and Egypt. British officers arrived in Cairo yesterday to interview Magdi el-Nashar, a biochemist linked to an address in Leeds, apparently used as a bomb factory. The Government is said to be resisting pressure to extradite the Egyptian national.
In Pakistan, students and teachers at a religious school believed to have been attended by one of the bombers were interviewed by intelligence officials. Two people were held in Lahore and four in Faisalabad on suspicion of aiding Shehzad Tanweer, whose bomb killed seven on the Circle line at Aldgate.
In Beeston, Leeds, the investigation moved to the Iqra Learning Centre, the bookshop where the three Leeds bombers are thought to have met. Police were last night given extra time to question a man who is believed to have worked at the shop.
Police also took over a seventh property in the Beeston area, a terraced house 50 yards from Tanweer's home on Tempest Road but barriers were removed from other houses, including that of an initial bomb suspect, Ejaz Riaz, on Stratford Terrace. His brother Naveed is still thought to be helping police in London.
A terror summit at Scotland Yard last Tuesday agreed new strategies to prevent further attacks, a senior police officer has told the IoS. "We are revising the manual on how to prevent other attacks. We have to look at what we have got to do to deter these terrorists and to make them frightened of being caught."
Security officials fear that terrorists may next target buildings and tourists, especially in central London. They stress, however, that no information has warranted a warning.
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