Investigators of the Ahmedabad [Images] serial explosions and the planting of bombs in Surat [Images] have found a new trend among terrorists strapping explosives with gas cylinders, a move to multiply the damage.

"We have found live bombs linking with gas cylinders. This is a new trend which we have witnessed in Gujarat," a senior National Security Guard (NSG) official said.

"The trend of using nails, screws, ball bearings and bags are similar with previous blasts which rocked different parts of the country. But placing of gas cylinder along with the bombs was new," he said.

On July 27, two WagonR cars were recovered from Surat with full of explosives and gas cylinders. However, the bombs were defused before they could explode.

Explosive experts of the NSG were sent to Karnataka and Gujarat to help the local authorities in investigations into the serial blasts.

"Our team from Gujarat is yet to return. But whatever preliminary information we have received so far pointed out a larger modus operandi by the perpetrators," the official said.

 Asked whether the NSG is fully equipped to deal with the recent trend of planting a large number of bombs at a single place on a single day, the official said it has adequate equipment as well as trained personnel.

 "NSG is fully equipped with latest technology and trained personnel," he said.

The NSG official, however, admitted that it does not have a forensic laboratory to deal with chemical explosives.

"But India has good forensic laboratories and experts in different parts of the country to deal with emergency situation," he said.

Asked about the possibility of involvement of external agencies being involved into the recent series of explosions, he said the local police were investigating all such aspects.