Islamabad:  At least 53 people were killed and 266 injured in the Marriott Hotel suicide truck bombing in the Pakistani capital, the government said yesterday, a day after the devastating attack termed Pakistan's 9/11 by a minister.

The dead included two US officials as well as the Czech ambassador to Pakistan and his girlfriend, Interior Ministry head Rehman Malek told a news conference.

Eleven foreigners - four from US, one from UK, four Saudis, one Lebanese and one Afghan - were among the injured, said Malek.

The luxury hotel located in a high security zone close to the Parliament, the Prime Minister's House, the Presidency and the Supreme Court, was "the target of the bomber," the top official said.

He discounted reports that the target was the Parliament during Saturday's maiden address to the House by President Asif Ali Zardari, who left yesterday for London en route to New York for the UN General Assembly.

While security sources believed Al Qaida was behind the terror strike, Malek said the past wave of suicide attacks were linked to the militants in the tribal region of South Waziristan.

"The investigations into the attacks in the past showed that all roads led to South Waziristan," the stronghold of tribal rebel commander and chief of Tehreek-e-Taliban, who is also blamed for last year's assassination of Benazir Bhutto in Rawalpindi near here.

Six-wheel truck

He said up to 600kg of explosives mixed with aluminum powder and phosphor was packed in a six- wheel dumper truck, a vehicle used for transporting boulders and stone crush to building sites.

Malek said the movement of such trucks was allowed after sunset to construction in the capital and the bomber availed of this opportunity to carry out his mission.

Security sources said camera recordings revealed that the bomber broke through the outer entrance barrier. As the truck went on, he exploded a grenade which he carried on his body, blowing himself up and putting the front cabin of the vehicle on fire.

"The guards tried to extinguish the fire and after about minutes it spread to the rear of the truck, triggering the big bang," a security official said.

It appeared that the bomber out of inexperience or anxiety could not set off the explosive load with the grenade or some other device, he said.

Malek said the army operations in Bajaur tribal area over the recent weeks had succeeded in "liberating" the district from the control of militants. Fighting in Bajaur has displaced hundreds of thousands.

He said the aluminum in the explosive produced a chemical that put on fire most of the 290 rooms of Marriott, a part of a US based international chain.

Malek reiterated the government would live up to its commitment to rooting out terrorism, which he said is the biggest threat to the country's nascent democracy.