It is understood that the two men arrested in the raid knew the informant, and that an MI5 handler checked out his story as "plausible". This contradicts previous reports which suggested that the information came from foreign sources and was received by the intelligence services.
There was growing criticism yesterday of the police operation after they released the two men they had been holding under anti-terrorism laws.
Mohammed Abdul Kahar and Abul Koyair were in police custody for a week after being detained in a dawn raid on their house in east London. The original raid involved 250 officers who had been told to search for a chemical bomb.
Lawyers acting for the two men said that they were now trying to put their ordeal behind them. "There is a lot of recovering to be done," said Gareth Peirce of Birnberg Peirce and Partners. "Abul Koyair should really be recovering in a hospital."
The police could face a huge compensation claim from the two men, especially Mr Koyair who was shot and injured. There is also considerable damage to their house, which was taken apart by officers.
Murad Qureshi, from the Metropolitan Police Authority, said that the Met needed to learn from a "series of mistakes".
He said: "They cover everything from the collection of intelligence and how you corroborate that, to the nature of the surveillance of suspects, through to how the suspects are actually dealt with, particularly in this case - how we find ourselves with one of the brothers shot and quite a lot of the slander that has been out in the press."
There are many questions which have yet to be answered, such as how did one of the suspects get shot and why police did not take more time checking the veracity of the intelligence that they received.
The Independent Police Complaints Commission is carrying out an investigation into the discharge of a single shot. It is expected to take several weeks before the results of forensic tests are known.
The most plausible theory is that the gun went off accidentally during a struggle on the narrow stairs and during the confusion that followed the raid.
Police have defended the pre-dawn raid by almost 250 officers, saying that they were responding to "specific intelligence" that one of the men had built an explosive device.
The Metropolitan Police has been quick to apologise for the anger they have caused to the Muslim community for what have been described as heavy-handed tactics.
Muslim residents in Forest Gate who know the two men have warned that the raid has caused lasting damage. Rizwan Aslam, a neighbour, said: "I heard Kahar was in prison before, but after that he changed completely and is a very nice guy. I think they were raided because they are Muslims with beards."
Additional reporting by Martin Hodgson
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