Mr. Blair used his address to parliament to offer condolences to the victims, to praise London's emergency workers and to express his rage against the terrorists who perpetrated the bombings.

"We express our revulsion at this murderous carnage of the innocent," he said. "We send our deep and abiding sympathy and prayers to the victims and their families. We are united in our determination that our country will not be defeated by such terror, but will defeat it, and emerge from this horror with our values, our way of life, our tolerance and respect for others undiminished."

Mr. Blair says London appears to be the latest target of a global campaign by Islamic terrorists.

"It seems probable that the attack was carried out by Islamist extremist terrorists, the kind who, over recent years, have been responsible for so many innocent deaths in Madrid, Bali, Saudi Arabia, Russia, Kenya, Tanzania, Pakistan, Yemen, Turkey, Egypt, Morocco, of course, in New York on September 11, and in many other countries, too," he said.

The prime minister says there were no evident failures by British intelligence, which, in the past, has successfully broken up several suspected terrorist plots.

But Mr. Blair said additional counter-terrorism legislation could be introduced to help authorities deal with the problem. Britain is already moving to introduce national identification cards, though authorities concede the cards would not have necessarily prevented last Thursday's attacks.