Patna, Jun 24 (IANS): The Bihar Home Department is expected to transfer the June 17 Darbhanga train blast case to the National Investigation Agency (NIA), a source said on Thursday.

The incident at the Darbhanga railway station occurred when a packet containing chemicals exploded soon after it was taken away from the parcel compartment of a train arriving from Secunderabad.

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

"During investigation, there was a hint of ISI connection in it. The joint report of Bihar and Telangana ATS is expected to be sent to the Union Home ministry tonight (Thursday night) to tomorrow (Friday) morning. We believe that case will be soon transferred to NIA," an official of Bihar ATS, requesting anonymity, said.

Sources have said that four suspects are arrested in this case. They were arrested from different states and their identities and places where they were nabbed are not being revealed due to security reasons.