RAWALPINDI, Dec 24: Experts investigating the Rawalpindi bomb blast in which President Pervez Musharraf’s convoy narrowly escaped recently, have determined that a “plastic explosive” was used to blow up the bridge, a source told Dawn.

However, the type of the plastic explosive, which the experts believed was used for the first time in Pakistan, is yet to be determined.

“It is yet to be determined whether it was the same kind of explosive used in the Bali bombing,” the security official said.

The official said sniffer dogs usually caught fumes of a normal explosive but in this case they failed to detect it.

After the incident, sniffer dogs were brought to the bridge by military experts on different occasions but they failed to lead the investigating team to trace a clue to the terrorists, the source added.

Another security source said the final report, comprising the views of bomb disposal experts and statements of security personnel deployed on the VVIP route, was yet to be finalized.

Meanwhile, the police personnel, who had been on the president’s route duty and were taken into custody by the army investigating team after the blast, are still being questioned.

In another related move, the authorities have revamped security arrangements for the president. A security source said as part of the revised security plan, the security personnel were deployed on five different roads leading towards Islamabad from the Army House, Rawalpindi.

He said President Musharraf had also started occasional use of helicopter for going to Islamabad.