While the police have confirmed the use of ammonium nitrate in the Bengaluru serial blasts, investigations have revealed that traces of a relatively new substance called ammonium picrate has also been found in the bombs.

The investigating agencies say that the bombs were made from ammonium nitrate, picrate, fuel, nuts, bolts and were connected to an embedded chip that was used to trigger off the blasts. The use of ammonium picrate has foxed investigating agencies as the substance is not easily available in the open market.

Ammonium picrate, which is usually found in a powder form, is also known as explosive D. It is used in the military and was used extensively in both the world wars.

It is considered to be least sensitive to shock and friction.

During military operations, it is loaded in a shell and fired through an armour plate. Explosive D was used in the bombs to ensure maximum damage, proving that the police were wrong in assuming that the Bengaluru [Images] blasts were only meant to scare people.

The police feel that while the rest of the material used to put together the bombs may have been purchased locally, the ammonium picrate was sourced from another country.

According to the police, it is not easy to purchase ammonium picrate as very few industries manufacture the substance and it is only supplied to the military.