The four suspected bombers have been on the run now for nearly a week – although unconfirmed reports suggest one of them has been arrested in Birmingham.
British Prime Minister Tony Blair has responded angrily to suggestions that London was targeted in part because of the Iraq war, insisting the world should not “give one inch” to terrorism.
Police are testing substances found at a London apartment linked to the bombings on July 21, in which four suspected would-be suicide bombers fled after their devices failed to fully detonate.
The ninth floor apartment in a tower block in the north London suburb of Southgate was raided early Monday.
Neighbours said later they had seen two men identified by police as suspected bombers at the address, labelled by some British newspapers a “bomb factory on the ninth floor”.
Police have named two of four suspects; 27-year-old Muktar Said Ibrahim, also known as Muktar Mohammed Said, and 24-year-old Yasin Hassan Omar, captured on security cameras near the sites of the July 21 wave of blasts.
Meanwhile police have seized a car in the East Finchley area of London, not far from Southgate, in connection with the July 21 blasts.
The focus has switched from Stockwell in south London, where a series of suspects were arrested over recent days.
It was also there that an innocent Brazilian electrician was shot dead by police on Friday after a chase through a subway station, a major setback for investigators.
Police have now arrested five men in connection with the attacks but none are believed to be among the suspected bombers.
At a Downing Street press conference, a combative Blair rounded on critics of his Iraq policy, insisting nothing could excuse terrorist attacks.
“I want to make one thing very clear to you. Whatever excuse or justification these people use, I do not believe we should give on inch to them,” he said.