LONDON – New laws to catch people planning acts of terrorism will be fast-tracked through Britain’s Parliament if the police and security services investigating the London bombings want extra powers, Prime Minister Blair promised yesterday.

As the death toll rose to 52 and the first victim of the blasts was named, Mr. Blair said the government was considering clamping down on radical Muslim clerics who were “inciting hatred.”

Meanwhile, millions of Londoners went back to work yesterday – many traveling by public transportation. “We won’t let a small group of terrorists change the way we live,” the city’s mayor, Ken Livingstone, said, according to the Associated Press. President Bush expressed a similar sentiment, saying yesterday, “America will not retreat in the face of terrorists and murderers.”

Mr. Blair promised one of the most “vigorous and intensive” manhunts ever seen to find those responsible for Thursday’s bombing of three Underground trains and a double-decker bus.

Hundreds of detectives are working on the hunt, securing closed-circuit television footage from all stations through which the trains passed and on the route used by the no. 30 bus on which a bomber is thought to have blown himself up, possibly accidentally.

Mr. Blair said it seemed probable that the bombs had been planted by “Islamist extremist terrorists” of the kind responsible for the attacks of September 11, 2001, and those last year on trains in Madrid.

Britain’s senior finance minister and a member of Mr. Blair’s Cabinet, Chancellor Gordon Brown, said the government would do “whatever it takes and spend whatever is necessary” to defend the public.

The Conservative leader, Michael Howard, and other members of Parliament cast aside normal party politics to praise the “resolute and statesmanlike” way Mr. Blair had responded to the tragedy.

Mr. Blair promised to seek cross-party consensus on any new anti-terrorism laws, including measures to catch and convict those helping to plan terrorist activity, or glorify and condone acts of terror.

The government’s current plan is to publish an anti-terrorism bill for prelegislative scrutiny this autumn and introduce it in Parliament next spring. That means that it might not be on the statute book for another year.

But Mr. Blair said that if it became clear as the investigation proceeded that the police and security agencies needed new powers immediately, the government would accelerate the timetable.

He told members of Parliament that a two-minute silence would be held throughout the country on Thursday, with a memorial service attended by Queen Elizabeth to be held at a date to be arranged.

[Tensions remained high in London, and police briefly closed several streets where most government offices are located – including Parliament, the Foreign Office, and 10 Downing St. – after a suspicious package was found, but it contained no explosives, the Associated Press reported. Later, police evacuated the King’s Cross subway station for a time and shut the Waterloo bridge over the River Thames; both were false alarms.]

All 12,000 American airmen based in Britain have been banned from going near London because of the bombings.

The directive, issued on Friday, indefinitely bans U.S. Air Force personnel, most of them based at the huge airfields at Lakenheath and Mildenhall in Suffolk, from going inside the M25 highway that runs on the outskirts of the city. Families of the servicemen and women are being “highly encouraged” to stay away, too.

While the mayor of London, Ken Livingstone, was boarding an Underground train yesterday and declaring that “we don’t let a small group of terrorists change the way we live,” an Air Force spokesman said the ban was “a prudent measure.” Its aim was to ensure “the security and safety of our airmen, civilians, their families, and our resources.”

The number of confirmed deaths was 52, Scotland Yard said, although Mr. Blair indicated that it could still rise.

Fifty-one bodies have been removed from the scenes of the bombings and one victim died in hospital last week. Mr. Blair said that 74 families, including relatives of badly injured passengers, were receiving help from police family-liaison officers.

All bodies have been recovered from the trains at Liverpool Street and Edgware Road and from the scene of the bus bombing in Tavistock Square and all “visible bodies” have been recovered from the Piccadilly line near King’s Cross.

The Metropolitan Police commissioner, Sir Ian Blair, acknowledged the distress and frustration of families who had been waiting to learn the fate of those still missing.

“I appeal to everybody to give us time,” he said. “We will identify people as quickly as we can but this is the biggest crime scene in English history and we have got to get it right.”

Sir Blair emphasized that the police, who are answering to the Westminster coroner, Dr. Paul Knapman, were faced with a slow process of identification.

It involved finding forensic proof, including dental records, fingerprints, and DNA, or corroborative material – such as relatives’ descriptions or documents found on bodies – to establish the identity with certainty.

Much of the difficulty has arisen because of the mutilated state of the bodies, many ripped apart by the force of up to 10 pounds of high explosives in confined areas. However, sources said they hoped to complete many identifications by the weekend.

Susan Levy, 53, was the first victim to be named formally yesterday. An inquest was opened and adjourned.