Patna, Jun 28 (IANS): The Anti Terrorist Squad (ATS) of Bihar Police is likely to re-investigate the parcel blast at Darbhanga railway station, a police source said here on Monday.

The ATS has sent samples to Kolkata for forensic test. A Bihar police official said that the experts from FSL, Pune will also join in the investigation in Kolkata.

At present, ATS Bihar, Telangana and Uttar Pradesh police are jointly investigating the case. Besides, National Investigating Agency (NIA) is also doing parallel investigation.

The explosion at Darbhanga railway station took place on June 17 when a packet containing chemicals exploded soon after it was taken away from parcel compartment of a train which arrived from Secunderabad, Telangana.

As the matter was very serious, GRP transferred this case to Anti Terrorist Squad (ATS) of Bihar police. As the matter was related to Telangana and Uttar Pradesh, the ATS of these two states are also investigating the case.

"Preliminary investigation has revealed that it has some connection with Pakistan's ISI. We have arrested four suspects in this case and it has appeared that ISI had done the funding. The scanning of bank accounts of suspects are underway," an officer of Bihar ATS said.

"We have arrested them from different states and their identities and places from where they were nabbed, are not revealed due to security reasons," he said.