A huge suicide truck bomb devastated the heavily guarded Marriott Hotel in Pakistan's capital Saturday, killing at least 40 people and injuring up to 200.

The blast left a vast crater some 20 feet deep in front of the main building. Rescuers ferried a stream of bloodied bodies from the gutted structure - which rescuers feared could collapse.

The five-floor Marriott is a favourite place for foreigners as well as the Pakistani elite to stay and socialise, despite repeated militant attacks over the years.

Two hospitals said 10 foreigners were among those being treated by them, among them 4 Britons and one each from Germany, Saudi Arabia, Morocco and Afghanistan.

Senior police official Asghar Raza Gardaizi said the blast, which reverberated throughout Islamabad and shattered windows many hundreds of yards away, was caused by more than 2,200 pounds of explosives.

The attack came hours after new President Asif Ali Zardari addressed Parliament for the first time. In his speech Zardari vowed not to let terrorists use Pakistani territory. However, he also warned that the government would not allow "any power" to violate Pakistan's sovereignty - a reference to U.S. strikes across the border from Afghanistan that Pakistan warns will fan Islamic extremism.

Zardari and Prime Minister Yousuf Raza Gilani condemned the attack as a "heinous crime" and said those behind it would be brought to justice.

The country faces a raging insurgency by the Pakistan Taliban in the border areas, where al-Qaeda militants are also operating.

Witnesses said they saw a large truck drive up to the fortified main gate of the hotel at about 8 p.m. when its restaurants would have been packed with diners, including Muslims breaking the Ramadan fast.

Mohammed Asghar, a worker from a nearby office with a makeshift bandage round his head, said there was more than one man in the truck and that they had argued with the hotel guards.

"Then, there was a flash of light, the truck caught fire and then exploded with an enormous bang," he said.

The hotel lies just off a busy thoroughfare, less than a mile from the presidential offices and Parliament.

Scores of people, including foreigners, ran or staggered out following the blast, some stained with blood.

British Foreign Secretary David Miliband said the bombing will only reinforce Britain's determination to combat terrorism in the country.

"This latest bombing attack in Islamabad is yet another shocking and disgraceful attack without justification," said Miliband. The White House condemned the attack calling it a "reminder of the threat we all face."

"The United States will stand with Pakistan's democratically elected government as they confront this challenge," said White House spokesman Gordon Johndroe-AP