Scotland Yard is tracking a number of potential terrorist suspects who may be planning further attacks, according to the senior police officer.
In his first full interview since the July 7 atrocities, Assistant Commissioner Andy Hayman said none of the individuals was linked to the blasts on July 7, or the attempted bombings two weeks later.
No master plot had been discovered, but Mr Hayman said that the force, and Londoners, would have to accept that the city was now a prime target. He anticipated other terrorist cells, which may well be British, would launch attacks.
"I don't want to scaremonger but it has to be said, when you look around the world and at the prominence of London, that the threat is real," Mr Hayman told.
"We always remain active in covert operations. We have a number of people who are of interest."
He added: "London is an iconic site as a location for another terrorist attack. We have to be vigilant but you can't predict where or how or when they will try."
Mr Hayman also admitted that getting the Muslim community to trust the police was proving a long and difficult process, Guardian reports.
Photo: the AP
The shooter freely entered the building of the university and opened fire at those who were present on the ground floor