An FIR has been registered on Thursday in connection with the low-intensity blast in the toilet of a general compartment of Kanpur-Bhiwani Kalindi Express at Barrajpur railway station near Kanpur on Wednesday.
The FIR was lodged by the guard of the train with the Government Railway Police (GRP) at Farrukhabad railway station.
The FIR was registered against unknown persons and under Section 151 of Railway Act, sections 3/4 of Explosive Substances Act and Section 286 of the Indian Penal Code.
The GRP said that more sections could be included in the FIR later.
During preliminary investigation, the police had recovered a letter purportedly issued by terror outfit Jaish-e-Mohammad.
Subsequently, senior officials and a team of Bomb Disposal and Detection Squad and sleuths of Anti-Terrorists Squad also inspected the scene.
GRP officials confirmed that a case was registered and that the ATS was probing the case but declined to give details.