Following a directive of the home ministry, the NIA has lodged the case under various sections of the Unlawful Activities Prevention Act and Arms Act, an official statement said.
Three members of the Ansarullah Bangla Team (ABT) -- Samsad Mia alias Tanvir, Rizaul Islam alias Riyaz, both residents of Bangladesh, and Monotosh Dey alias Mona Da, a resident of West Bengal -- were arrested by the Special Task Force (STF) of Kolkata Police on November 21, 2017.
Subsequently, one more Bangladeshi national -- Umar Farukh alias Md Aftab Khan -- was arrested on November 28, 2017 in connection with the case.
The ABT is a proscribed terrorist organisation in Bangladesh.