The decision was taken at a high-level meeting with the Special IG, CID, Damayanti Sen at the state secretariat, Director General of Police, GMP Reddy, told reporters here.
"All police stations in the state have been asked to maintain a strict vigil against any subversive activity or attempt at sabotage," Reddy said.
Asked if they were suspecting involvement of any terrorist outfit in the blast, Reddy said, "We are not ruling out any possibility. Everything is being looked into."
Meanwhile, with the arrest of another person in connection with the blast, the number of those apprehended in the case has gone up to three.
Hafez Mollah alias Hasan, who was yesterday detained by CID from his house at Khar Duttapa in Purbostholi, about 70-km from here, was formally arrested today.
Two women were also arrested yesterday in connection with the blast in which the involvement of terror outfits like LeT and HuJI is being suspected.
The state shares international borders with Bangladesh, Bhutan and Nepal. It also shares boundaries with the Indian states of Jharkhand, Bihar, Odisha, Sikkim and Assam.
