The British police and security services were last night pinning their hopes for an early breakthrough in their search for those behind Thursday's bomb attacks in London on evidence from the shattered Number 30 bus and its passengers, both living and dead.
Anti-terrorist and security officials indicated that the three synchronised bombs on the Underground were placed by individuals who then fled and are still at large. This has led to a warning from the home secretary of possible further attacks as the total of dead was expected to reach 60.
The key to the investigation is now seen to lie in the bomb on the bus, which went off about an hour after the Underground explosions, killing 13 passengers as the bus passed through Tavistock Square.
Police are now almost certain the tube bombs were not suicide attacks, but were positioned at the doors of carriages before the perpetrators got off.
Among the theories being examined about the bus bomb yesterday is that it may have been a deliberate tactic to cause maximum mayhem as those fleeing the tube boarded buses. Another theory is that the device went off by accident as the bomber tried to make his way to another target.
Police sources said they could not rule out that the bomber may be among the dead, who have not been formally identified.
A number of passengers and the bus driver survived the blast, and detectives will be interviewing them at length in the hope that they can provide clues - all the more so as the bus's CCTV camera was not working.
Police will examine hundreds of thousands of hours of CCTV footage from tube stations and street cameras all over London today, in the hope this could yield pictures of the bombers. Scotland Yard set up a special e-mail address for witnesses to send mobile phone and video footage and photographs of the scenes.
There have already been 1,700 calls to the confidential anti-terrorist hotline, some of which, police said, contained important information.
Specialists from 30 countries are assisting the Metropolitan Police in their investigation. Spanish police have brought with them information about how the Madrid train bombings that killed 191 people were carried out last March. Security sources said they were keeping an open mind about who was responsible.
One person under scrutiny yesterday was Mustafa Setmariam Nasar, a Syrian linked to the Madrid bombers and said to be in Iraq, who was reported to have set up a "sleeper cell" in London.
A Spanish-nationalised Syrian who lived in north London from 1995 to 1998, Nasar was described by the chief prosecutor in the Madrid bombings case as a suspect in the attacks. Tall, red-haired, pale-skinned and green-eyed, Nasar has been able to travel without raising suspicion.
Security sources said they were pursuing a number of individuals. "No one name has risen to the top of the heap. They are all being looked at, all given equal weighting," a senior anti-terrorist official said.
Intelligence sources described a "very small number of inner-core al-Qaeda people" in Britain, consisting of 30 or so members, with several hundred who have been to training camps or have fought in Afghanistan, Bosnia or Chechnya. They referred to a third group of "home-grown" radicalised Britons not linked to the other groups and difficult to investigate and know about.
A joint Home Office and Foreign Office report, Young Muslims and Extremism, said Britain might now be harbouring thousands of al-Qaeda sympathisers. - (Guardian Service)