Yesterday, rescuers continued sifting through the rubble and the building shell in a search for possible survivors and human remains.

The bombing, which unleashed a fire that gutted much of the nine-storey building and littered several city blocks with debris, was the worst urban attack here in decades.

Rescuers worked meticulously and carefully, fearing that whole floors of the building could collapse due to structural damage.

Authorities have blamed leftist rebels with the Revolutionary Armed Forces of Colombia for the blast. The 17,000-strong rebel force, engaged in a four-decade-long war with the Colombian state, has recently stepped up its urban attacks.

Late on Sunday, President Alvaro Uribe called on Colombians for national unity against the attackers. "Colombia cries but does not surrender," he said.

Just before Uribe spoke, Justo Pastor Rodriguez, Colombia's national director of prosecutors, said that investigators have found a detonator belonging to what they believe was a second vehicle loaded with explosives that was in the building parking lot at the time of the blast.

Investigators believe that more than 150 kilograms of C4 explosives and ammonium nitrate were used in the blast.

Agents from the US Bureau of Alcohol, Tobacco and Firearms were called in to help in the investigation because of their experience with the 1995 bombing of a US federal building in Oklahoma that killed 168, Pastor said. "There seem to be significant similarities with the explosion in Oklahoma (City) and the one at El Nogal," he said.

(China Daily February 11, 2003)