Acting on a tip-off, a special team of the STF last night arrested Roy from the Sealdah railway station area when he was about to board a train to flee the city.
Roy, a state committee member of the CPI (Maoist), was being tracked by the STF for a long time.
Roy will be produced before the court tomorrow.
Asked if Roy is involved in any extremist activity carried out by the Maoists in the state, Joint CP (STF) Tripurari said, "The interrogation has just begun. Let it progress, then only we can say something,".