PETN may have been used: MHA

U K Bansal, Secretary, Internal Security, Union Home Ministry, said blast created a small crater at the place where the explosive charge is suspected to have been kept in a brief case near the reception of the High Court. "The examination of the scene of blast indicates the use of nitrate-based explosives with traces of PETN," he said.

PETN is one of the most deadly explosives which is used by terrorists world over, but is commonly used by both military and civilian contractors in tasks such as quarrying. Small quantities of the explosive can cause enormous damage.