All four July 7 London suicide bombers were tracked by intelligence services a year before the attacks, it was claimed today.
Quoting unnamed police sources, the Mirror reported that field agents had Shehzad Tanweer, Jermaine Lindsay, Hasib Hussain and Mohammed Sidique Khan on a list of 100 feared religious fanatics before the watch was called off because they failed to "fit the preconceived terrorist profile".
It is not the first time claims have emerged from likely whistle blowers that the four were not "clean skins" unknown to the security services, as was originally believed.
The BBC alleged last week that Khan, the suspected ringleader, was caught on film and recorded by the security services before the suicide bomb attacks on the capital's transport system that killed 52 people and injured more than 700.
He is reported to have been associating with people identified by western security services as being suspected of involvement in terrorism.
The BBC did not specify who its sources were or from which agencies they came, though they appeared to be from the counter-terrorism community.
Its report said that a man in custody in Indonesia said the 30-year-old former classroom assistant met a terrorist called Hambali, the alleged operations chief of al-Qaida-linked Jemaah Islamiyah, after travelling to Malaysia in 2001.
The detainee told academic researcher Rohan Gunaratna that he took Khan to meet and train with leaders from the extremist group blamed for the 2002 Bali bomb attacks.
The BBC report also linked Khan to a US-based Islamist, now in custody, who is alleged to have ties to al-Qaida and whom the BBC described as an "al-Qaida fixer".
The Mirror today claimed that security services had a fifth man, who is now believed to be in Pakistan, under surveillance.
The report came this morning as members of the London Assembly committee reviewing the handling of the attacks listened to a 999 call made to emergency services on the morning of the four bomb attacks.
In the recording the caller is heard describing the scene in Tavistock Square where Leeds-born Hussain detonated his device on the number 30 bus.
The caller told the police emergency operator that the double decker had just exploded outside the window, and went on to describe "people lying on the ground".
"I think there's ambulances on the way but there's people dead and everything by the looks of it," the distressed caller said, as emergency sirens sounded in the background.