LONDON, AP -Police and intelligence agencies missed chances to identify the suspected leader of the July 7 London transit bombings and one of his fellow suicide attackers who killed 52 people last year, a parliamentary report said Thursday.

Home Secretary John Reid also told the House of Commons that police and intelligence agencies had thwarted three attacks since July 7, and that the government was building up intelligence staffing “as fast as their top management believe is organizationally possible.”

Reid gave no details of the thwarted attacks, one of many questions left unanswered in report by the Intelligence and Security Committee, and by the Home Office.

The committee said British intelligence agencies had been aware of two of the eventual bombers — suspected leader Siddique Khan and Shazad Tanweer — before the attacks, but decided not to closely watch them because their identities were not clear and agents were busy examining “known plans” to attack Britain that were not specified.

The security services had come across the two “on the peripheries of other surveillance and investigative operations,” the report said.

“As there were more pressing priorities at the time, including the need to disrupt known plans to attack the U.K., it was decided not to investigate them further or seek to identify them,” the report said.

There was still no conclusion about al-Qaida’s role, if any, in organizing the attacks, though investigations were continuing, Reid said. Authorities are still puzzled about why one of the bombers, Hasib Hussein, stopped to buy a battery before killing 14 people on a double-decker bus.

Reid said the bombers were in touch with someone in Pakistan just before striking, but that nothing is known about what was discussed.

The Intelligence and Security Committee report concluded there were “no culpable failures” by Britain’s security services and no warning of the attacks.

However, the report also said authorities would have had a better chance of preventing the bombings had they channeled more resources into intelligence work in Pakistan and not underestimated the potential for British citizens to become terrorists.

“Neither the potential speed of radicalization nor the fact that British citizens could be radicalized to the point of suicide were understood” by security services before the attacks, said committee chairman Paul Murphy. “The committee are concerned that this could have had an impact on the ability of authorities to respond.”

“Greater coverage in Pakistan or more resources generally in the U.K. might have alerted the agencies to the intentions of the 7th of July group,” he added.

Three of the bombers’ families were originally from Pakistan and several had traveled there before the attacks.

“There are a series of suspicious contacts from an unknown individual or individuals in Pakistan in the immediate run-up to the bombings,” Reid said. “We do not know their content.”

He said the explosives left behind in a car in Luton, north of London, “may have been for self-defense or diversion in case of interception” during the journey to London from the Leeds area, where three bombers lived.

“They do not appear to indicate a fifth bomber,” he said.

It is estimated the bombers spent less than $15,000 to carry out the attacks, he said.

Reid gave no details of the plots he said had been thwarted since July. Peter Clarke, head of London’s Metropolitan police anti-terrorist unit, said in February that two planned attacks had been foiled since the bombings.

The report confirmed that Britain’s alert status had been downgraded from “severe general,” the second-highest, to “substantial” on May 26, 2005

“The main reason given … was that there was no intelligence of a current credible plot to attack the U.K. at that time — i.e. a group with established capability and current intent,” the report said.

The committee said it found no links between the July 7 attackers and the group that mounted failed bombing attempts against the transit system two weeks later.

Reid said it was not yet clear whether anyone in Britain had indoctrinated the suicide bombers, but said bomber Jermaine Lindsay, a Briton of Jamaican origin, appeared to have been influenced by an extremist preacher who was now in jail. Reid did not identify the cleric.