LONDON - Commuters returned to work in London today, the start of the first full week since bombers killed at least 49 people on a bus and subway trains. Many travelers said they would defy the attackers by using public transportation as normal, but some were too afraid and took taxis instead.

"I ... will not let the attacks put me off," said computer consultant Paul Williams, 42, as he prepared to board an underground train in central London. "As far as I am concerned, it is just a normal day at work."

But Ted Wright, chairman of the British Poultry Council, said he was taking a taxi to avoid the subway system. "In light of what has happened, I have decided to take a taxi. It will probably cost an extra six pounds ($10.70), but should hopefully put my wife's mind at rest," he said.

Three bombs that exploded on subway cars and one that ripped apart a bus killed at least 49 people and injured 700 last Thursday.

Scotland Yard said today it had identified the first of the victims - Susan Levy, 53, of Hertfordshire, outside London. Forensics experts have warned that it could take days or weeks to put names to the bodies, many of which were mangled in the blasts.

Transit officials said the number of passengers using the system this morning was back to normal. However, a few sections of the underground rail system affected by the attacks remained closed, and the number of shoppers in central London has fallen by about 25 percent since the attacks, the British media reported.

Mayor Ken Livingstone took the subway to work today to send the message that Londoners should "carry on."

"We are going to work. We carry on our lives," he said. "We don't let a small group of terrorists change the way we live."

For investigators, today was another pressure-packed day of sifting through subterranean debris, checking tips from the public and identifying the dead and missing.

Police said three men - all Britons - arriving at Heathrow airport were arrested early Sunday, but immediately dismissed speculation of their having a break in the investigation. The three were released late Sunday night.

British intelligence officials met over the weekend with their counterparts from the United States, Canada and about two dozen European countries to brief them on the attacks and the investigation, police said today.

Security officials in Poland said today they searched the home of a British citizen of Pakistani origin in the eastern Polish city of Lublin in connection with the bombings. Poland's Internal Security Agency did not release the man's name and he was not arrested.

A man with British and Moroccan nationality mentioned as a possible suspect told The Guardian newspaper in an interview published today that he had nothing to do with the blasts.

"Over 30 years I have lived in Britain, I have never been involved in violence or crime," said Mohamed Guerbouzi, who was convicted in absentia in Morocco in 2003 and sentenced to 20 years in prison in connection with the Casablanca terrorist bombings.

"I'm scared for my safety," Guerbouzi said.

Police said they were still working to recover the remaining bodies from one of the trains damaged in Thursday's blasts.

More than 70 feet below the surface, teams of workers - clad in white suits and wearing face masks to protect them from the dust - dealt with sweltering heat and rats as they removed some of the bodies from the train wreckage in the tunnel between Russell Square and King's Cross.

It was unknown how many more bodies remained below, but searchers said conditions were unlike any they had encountered before.

The Rev. Nicholas Wheeler of the Parish of Old St. Pancras, who has been at King's Cross since Thursday, said Sunday that the toll on the rescue workers has been enormous.

"Obviously some are young people who have never seen horrors like this before, and they were emerging shell-shocked," he said.

On Sunday, Queen Elizabeth II led commemorations of the 60th anniversary of the end of World War II in Europe. Thursday's attacks were not forgotten, and in speeches, officials noted a determination that Britain had suffered worse and would survive its latest tragedy.

Investigators remained silent on suspects in the bombings, but reports in London newspapers Sunday identified a possible suspect as Mustafa Setmarian Nasar - a Syrian suspected of being al-Qaida's operations chief in Europe and the alleged mastermind of last year's Madrid railway bombings.

London police refused to comment, but a U.S. official said that both nations were trying to locate Nasar.