Pakistani security officials have disclosed new details about Saturday's hotel bombing and released a video showing the attack.  VOA's Barry Newhouse reports from Islamabad, where the interior ministry said the death toll has reached 53 people, including four foreigners.  

The top official in the interior ministry told reporters that the attackers had built a sophisticated bomb that is the largest on record in Pakistan.

Rehman Malik said an estimated 600 kilograms of military grade explosives were mixed with aluminum powder - a highly flammable material.  The bomb was packed inside a large dump truck that was also carrying construction materials - apparently to take advantage of city rules that allow large construction vehicles into the city after sunset.

Security camera footage released by officials showed a large truck attempting to ram the hotel gate.  When the truck failed to breach the barrier, the driver appeared to detonate a small explosion inside the cab, catching the vehicle on fire and sending hotel guards fleeing.  The vehicle then burned for several minutes, before the flames grew and eventually detonated the truck's massive payload.    

Rehman Malik said officials have made no arrests, but suspect the perpetrators are linked to previous attacks.

"Unless I investigate, Im not at liberty to tell you who has done it.  But previous investigations, all the roads have gone to South Waziristan," Malik said.

The tribal agency on the Afghan border is considered a stronghold of Taliban leader Baitullah Mehsud, who was also blamed in the assassination of former Prime Minister Benazir Bhutto.

Officials said the four foreigners killed in the blast included two Americans, a Vietnamese citizen and the Czech ambassador to Pakistan.

No militant groups have claimed responsibility for the attack, but in the past spokesmen for the groups frequently call television and radio stations to take credit and criticize the government.

Rehman Malik urged the media not to give the militants a propaganda victory.

"I am requesting and appealing to the media to stop the glorification of those - those militants who are killing your brothers, your sisters," Malik said.

The top official in the interior ministry said the government plans to continue its plan for combating militancy in the tribal regions by distributing development aid, negotiating peace deals with willing partners, and using military strikes when necessary.