played no part in the London bombings last July, instead they were planned on a low budget from information off the Internet, the leaked findings of an inquiry into the blasts revealed.
The Observer newspaper, reporting the leak, said the government probe into Britain's worst terrorist attack concluded that it was a "simple and inexpensive" plot dreamt up by four suicide bombers intent on martyrdom.
The first forensic account of the July 7 bombings, which killed 52 people, found it was the product of a small-scale operation by the four men alone rather than an international terror network, according to the Observer.
The newspaper cited the first draft of the government's definitive report into the blasts. The findings are due to be published in full in a few weeks.
"The London attacks were a modest, simple affair by four seemingly normal men, using the Internet," a government source told the weekly newspaper.
This conclusion will likely alarm the authorities by revealing Britain's vulnerability to an attack by such an inexperienced group.
'Weapons cost just a few hundred pounds'
Mohammad Sidique Khan, 30, Shehzad Tanweer, 22, Hasib Hussain, 18, and Germaine Lindsay, 19, are thought to have blown up three London Underground trains and one double-decker bus during the morning rush hour on July 7 by detonating bombs packed into rucksacks.
The official inquiry found that these weapons cost just a few hundred pounds (dollars, euros) to make.
It also discounted the existence of a fifth bomber - a theory that was raised following the discovery of an explosive knapsack in the car used by the four attackers and abandoned at a station north of London.
As for any possible support from the terrorist network Al-Qaeda, the inquiry dismisses a videotape of Khan -- the ringleader -- that emerged after the attacks and also featured Al-Qaeda deputy Ayman al-Zawahiri.
The Home Office believes the tape was edited following the blasts rather than before, The Observer said.
But the report did find that trips to Pakistan by Khan helped to inspire the four bombers.
It went on to explore the psychological behavior of the attackers - three of them Britons of Pakistani descent and the fourth, Lindsay, a Jamaican-born Briton who converted to Islam - in their final months.
400 terrorist suspects on the loose
The findings reveal how they led double lives, adopting an extreme interpretation of Islam while at the same time enjoying a Western lifestyle.
Concerns over Britain's foreign policy and the feeling that it was deliberately anti-Muslim prompted the group to attack, The Observer said, noting that they were also driven by the prospect of immortality.
While Al-Qaeda may not have had a hand in the July bombings, The Sunday Times said police and intelligence officials believe at least 400 terrorist suspects from the group - double previous estimates - are on the loose in Britain.
Dame Eliza Manningham-Buller, director-general of MI5, the country's domestic spy agency, warned that the figure could be as high as 600 because of suspects returning from training camps in Pakistan, Afghanistan and beyond.
Against this backdrop, Britain on Monday will open its first centre for developing methods to identify and handle suicide attacks and even roadside bombs, The Observer said.
Forensic experts, scientists and other specialists will use the centre at the government's chemical warfare research establishment at Porton Down, Wiltshire, southwest England.