Police urged Londoners to get back to work on Monday to show the suspected al Qaeda bombers who killed at least 49 people that they had not cowed the British capital into submission.

"London is open for business. If we don't do that, then the terrorists will have won and that's not what we want," said Deputy Chief Constable Andy Trotter.

Police, hunting the bombers who targeted three underground trains and a double-decker bus last Thursday, have warned that the forensic search for clues is a painstaking process that could take time.

Relatives of those still missing after the attacks kept up a desperate search for information. Walls close to King's Cross station, scene of the worst blast, were covered with photographs of missing people and appeals for news of them.

Interior Minister Charles Clarke conceded that Britons would inevitably be on edge until the bombers are caught.

"The most important thing is to find the people who committed the attacks. Once that happens, people will feel they are more certain in where they are," he said.

"Our fear is, of course, of more attacks until we succeed in tracking down the gang that committed the atrocities on Thursday," he said.

The United States has sent FBI forensic experts to help British police analyze the crime scene, which British and American authorities say bears the hallmarks of the al Qaeda network that attacked the United States on Sept. 11, 2001.

"I think we are proceeding on the assumption that the bombers are still at large and of course that adds a special urgency to figuring out who's done this," said US Homeland Security Secretary Michael Chertoff.

Security analysts said the bombers, if cornered, could be deadly.

"In the immediate future, they will be lying low but the authorities will be searching intensely for them," said Dominic Armstrong, head of research at security company Aegis Defense Services.

"The more extreme Islamist operating instructions dictate that, if faced with capture, they should kill themselves and take as many of the enemy with them as they can. This happened in the aftermath of the Madrid train bombs (in which almost 200 died last year) and could well happen in London," he said.

Police, searching for clues in London's deadliest peacetime bomb attack, have urged the public to e-mail photographs and video footage taken with digital cameras or mobile phones at the bomb sites.

"These images may contain crucial information which could help detectives in what is a painstaking and complex inquiry," said Peter Clarke, head of London's Anti-Terrorist branch. Investigators have also asked mobile phone and Internet companies to store the content of voicemails, emails and SMS text messages that were in their systems on the day of the London bombings, a police source told Reuters.

Police said they had arrested three people under terrorism laws at London's Heathrow airport on Sunday but had no cause so far to link them to the bombing. The three men, arrested on arrival in Britain, were later released without charge.

(Chinadaily.com via agencies July 11, 2005)