IEDs similar to ones used by IM: police

The explosive materials used to trigger the low-intensity blasts in Pune were ammonium nitrate and fuel oil, said sources in the Central Forensic Science Laboratory.

The explosive materials used to trigger the low-intensity blasts in Pune were ammonium nitrate and fuel oil, said sources in the Central Forensic Science Laboratory.

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Also, the devices were similar to the ones used by the Indian Mujahideen in previous blasts. The only difference was that it was packaged differently, said forensic experts.

The explosives were kept in a cardboard box, similar to ones found in cake shops.

On Thursday, the Pune police had said the explosive devices were made of digital timers, nine-volt batteries, detonators, and white and pink substance. “The white and pink substance is ammonium nitrate,” said a forensic expert.

The state forensic science laboratory is identifying which chemical was used as the booster. “The circuit used in the explosives seems to be perfect. But it did not have the desired effect either because the proportion of the mixture was not right, or there was a problem with the booster or detonator,” the expert said. A report into the kind of explosive that was used has to be sent to the ministry of home affairs by Saturday, said police sources.

According to the police, though the IM uses cheap and readily available chemicals such as ammonium nitrate, they constantly change and enhance their improvised explosive device. “They started with pressure cookers in Mumbai in 2005 with analog timers, and graduated to tiffin boxes at Varanasi in 2006. In 2008, they used C-shaped explosives in Ahmedabad, and tried a circuit with digital timers with integrated circuit chips in Surat,” said a senior police officer.

A mobile phone alarm was used to conduct the German Bakery blast in 2010, and TNT was used as a booster in 13/7 Mumbai blasts, the officer added.