A senior Tory MP has called for an investigation into whether MI5 mistakenly recruited al Qaida sympathisers.
Patrick Mercer, chairman of the counter-terrorism sub-committee, told the Telegraph six Muslim recruits were thrown out of the service because of serious concerns about their pasts.
The MP said he was writing to Home Secretary Alan Johnson to call for an investigation into the matter.
Two of the six allegedly attended al Qaida training camps in Pakistan while the others had unexplained gaps of up to three months in their CVs.
Mr Mercer said the terrorist attacks on America should have prompted the Government to expand the security services, but this did not happen until the bombings on London's transport network on July 7 2005.
"In fact it took an attack on this country for such measures to be started," he said.
"But at this point it was an unseemly rush of which our enemies, not unsurprisingly, took advantage."
Mr Mercer added he was concerned that al Qaida sympathisers who may have infiltrated the security services had not all been rooted out yet.
Mr Mercer said the two recruits who had allegedly been to training camps were not dismissed until after they had been given several weeks of training at MI5.
But the others were identified before they started training.
