While the materials discovered by police are commonly used as components in terrorist bombs, Chulalongkorn University Associate Professor Panitan Wattanayagorn said the authorities had exaggerated the power of the material confiscated, thus raising more questions than answers.

He said the overall composition of the explosive materials contradicted the government's claim that the so-called bomb plot to assassinate caretaker Prime Minister Thaksin Shinawatra was the work of a highly sophisticated outfit looking to wipe from the face of the earth everything within a one-kilometre radius.

Panitan pointed out that the assembly of bomb material appeared to be "very sloppy", and that the "wiring and ignition

were very makeshift, crude and basic".

He said the amount of explosive found was enough to cause damage up to a radius of no more than 100 metres, not the one kilometre, as claimed by the authorities.

Combined, the confiscated materials - 67 kilograms of ANFO (ammonium nitrate and fuel oil), 1.5kg of C4 and about 4.8kg of TNT - were designed to take down an installation or a small building, and not to wipe out everything within the stated range, he said.

The composition of the Bali bomb in October 2002 that killed more than 200 people, for example, had more than 300kg of blasting agents in each of the three vehicles.

Panitan said it was just as important that each of the Bali vehicles was situated near a "critical structure" in order to create the most impact. This aspect was lacking at the Thursday incident, he said.

TNT blasting pressure is very high with a velocity of 6.9km per second. But the initial blast from 4.8kg would not be enough to keep the 67kg of ANFO burning for any significant length of time - and certainly not as far as one kilometre from the point of the blast, he said.

"Any effect beyond the initial impact area would be significantly weakened," said Panitan.

Don Pathan

The Nation