Kolkata, May 8 (IANS): Preliminary investigations showed that the house in West Bengal, where an explosion claimed 12 lives, housed a fire cracker factory and there was no evidence that bombs were manufactured there, police claimed on Friday.

"Preliminary investigation shows it was a firecracker making factory. We have found small and big crackers and the ingredients to make them," said Deputy Inspector General (Operations) of West Bengal Police Criminal Investigation Department Dilip Adak.

The officer, who visited the spot, denied any of the injured had splinter injuries. "Not a single splinter was found at the spot," said Adak.

"We have found small stone chips which are needed to make crackers," said Adak.

He said experts from the Kolkata-based Central Forensic Science Laboratory had already inspected the spot and taken samples. "They will examine and give their report. Then we will know more details."

He said 11 of the 12 people who died in the blast have been identified by one of the injured.

Apart from tenant Ram Maity and his wife, all others are from Suti in Murshidabad district.

"One of the bodies was charred beyond recognition," said Adak.

He said police also stumbled upon aluminium powder, used in making sparklers.

The explosion on Wednesday night ripped through the house at Brahmanbar village in the Pingla area of West Midnapore district.

Chief Minister Mamata Banerjee ordered a probe by the Criminal Investigation Department (CID), but the BJP has demanded that the National Investigation Agency (NIA) be called in, claiming that it was a terror act, similar to the Burdwan blast on October 2 last year in which two Jamaat-ul-Mujahideen Bangladesh militants were killed and another was injured.

The Congress also called for the NIA.

Local residents in Pingla said the house was used for making crude bombs.