A suicide bomber rammed a truck packed with over half a tonne of explosives into the outer security gates of the luxury hotel on Saturday night, killing at least 60 people and wounding more than 260.

'The national assembly speaker had arranged a dinner for the entire leadership, for the president, prime minister and armed services chiefs at the Marriott that day,' interior ministry chief Rehman Malik told reporters.

'The president and the prime minister changed the venue to the prime minister's house. The function was not held at the Marriott, thus the whole leadership was saved,' Mr Malik added.

The hotel was instead hosting its regular meal for the breaking of the Ramadan fast at the time of the explosion.

The Marriott hotel is close to parliament - where Pakistan's new president Asif Ali Zardari on Saturday gave his first address since his election - and the residence of Prime Minister Yousuf Raza Gilani.

Pakistani investigators say they are searching for an Islamabad-based cell of Al-Qaeda militants believed to have carried out the bombing.

Dramatic video footage of the attack showed the attacker had failed to get through a barrier when he crashed his truck into the hotel's security gates.

He detonated a small bomb in the cab and guards struggled to put out the resulting blaze, the footage showed, before a gigantic blast turned the hotel into a fireball. -- AFP