Shaikh Umar Bakri Muhammad, the head of the London-based group al-Muhajirun, added on Sunday in an interview with the Portuguese daily Publico that last month's deadly Madrid train bombings were carried out by a group of independent actors who back Usama bin Ladin's organisation.
"There are many youths who dream of joining al-Qaida, but worse than that, there are many 'freelancers' who are willing to launch operations similar to those by al-Qaida," he said. "The attack in Madrid was carried out by one of those groups."
"Here in London there is a very well-organised group, which
calls itself al-Qaida-Europe," he added. "I know they are on the verge of launching a big operation."
Bakri Muhammad, who is suspected of having links with Abu
Qatada, an alleged al-Qaida leader in Europe, said it was
"inevitable" that London would be hit by a large attack "because they are being prepared by various groups."
Police in Britain have arrested several suspects since the discovery of the deadly poison, ricin, in a north London apartment in January.
Spanish authorities meanwhile have blamed al-Qaida, the hardline group headed by Usama bin Laden, for the 11 March commuter train bombings which killed 191 people and injured around 1900.