The CID has also conducted raids at different places in neighbouring states in connection with the case.
The NIA on Tuesday registered a case to probe a recent bomb explosion at a railway station in West Bengal's Murshidabad in which 22 people including state minister Jakir Hossain were injured, an agency spokesperson said.
The case was registered under relevant sections of the Indian Penal Code and the Explosive Substances Act at the Azimganj GRP police station in Murshidabad district on the basis of a statement of an eyewitness, the spokesperson said.
The incident happened on February 17 when an explosion took place at Nimita railway station, leaving 22 people injured.
The West Bengal CID has been investigating the case and has arrested two persons including one Bangladeshi national.
The CID has also conducted raids at different places in neighbouring states in connection with the case.
The minister and others are currently undergoing treatment at a state-run hospital in the city.