Rescuers picked their way yesterday through the smouldering ruins of the Marriott hotel in Islamabad, looking for more bodies after a huge bomb devastated the building in one of Pakistan’s worst terrorist attacks.

The death toll last night stood at 53, with 266 wounded, after a bomber blew up a lorry containing 600kg of explosive on Saturday evening. The body of Ivo Zdarek, the Czech Ambassador, was among those pulled from the rubble. Mr Zdarek, 47, moved to Islamabad only in August. Two Americans, said to be US Defence Department employees, were also killed in the blast but their identities were not revealed.

The Danish intelligence agency said last night that one of its agents, a security advisor, was missing after the attack and was presumed dead.

The bombing happened after dusk on Saturday, when hundreds of people were dining in several restaurants inside the hotel. Closed-circuit TV footage showed the driver of the lorry ramming into the security gates but failing to breach a second barrier.

Rehman Malik, an Interior Ministry official, said that the attacker intended to drive into the lobby of the hotel and had apparently tried to convince the guards to lower the second barrier. When they would not, he blew himself up in the lorry’s cabin. The guards then tried to put out the fire in the lorry, and it was several minutes before the second, enormous blast devastated the Marriott.

Abdur Rehman, 45, who was on security duty, said: “The bomber fired several shots in the air when we tried to stop him, scaring us all away. Then after a few minutes the truck exploded with a massive blast, setting the building on fire.” Mohammed Latif, who was in the hotel car park, said: “The entire area was engulfed in thick smoke and pieces of glass and debris was flying all over. People, many of them stained in blood, came rushing out from a side gate.” Akbar Khan, a World Bank employee, was dining with friends at one of the hotel’s restaurants when he heard a thud, and then a huge blast. “I saw people scaling 12ft walls at the back of the hotel to save their lives,” Mr Khan, whose head and arms were injured, said.

Rescue teams searched the blackened building room by room but were hampered by fires still burning some areas 24 hours after the explosion. “There could be some charred bodies inside,” a senior official said.

At least two Britons were among the hundreds wounded in the attack, which had the luxury hotel in the capital’s high-security zone in flames for several hours, destroying the five-storey building. Both were discharged from hospital after treatment for minor injuries.

At the entrance to the Marriott, a favourite venue for foreigners, journalists and wealthy Pakistanis, a crater 50ft wide and 20ft deep bore witness to the power of the explosion.

Many of the victims were killed or injured by the intense heat of the blast, which also burst gas pipelines. “Bodies were charred beyond recognition,” a rescue worker said. Doctors at the city’s main hospital said that, with dozens of wounded in a critical condition, the death toll could rise.

No one has claimed responsibility for the attack, but investigators said that it bore the hallmarks of an al-Qaeda operation. “The purpose was to destabilise democracy,” Yousuf Raza Gilani, the Prime Minister, said. He added that Chechen, Uzbek or Arab militants operating from the border areas could have been involved.

Mr Gilani said that the bomber had attacked the Marriott only after tight security prevented him from reaching the Parliament building or the Prime Minister’s office, which are a few hundred yards from the hotel. The explosion took place just two hours after President Zardari had made his first address to Parliament, calling for terrorism to be rooted out. Mr Gilani, Mr Zardari, the chief of army staff and MPs were at a state dinner half a mile away when the bomb went off.

The Interior Minister suggested that Tehrik e-Taleban e-Pakistan (TTP), an militant group suspected to be linked to al-Qaeda , was involved in the attack.

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