A senior officer said the city police had received an intelligence report from Tripura that terrorists may conduct blasts in areas like Esplanade, New Market, Park Circus, Chowringhee and Gariahat between November 15 and 30.

Intelligence branch of the Tripura Police claim that suspected activists of Jamat-Ul-Mujahideen have already entered the city and a sleeper cell of a militant outfit is active in Kolkata.

Senior police officers have asked officers-in-charge of all 48 police stations to intensify vigil. They have been asked to keep watch on footpath-dwellers who, according to the intelligence report, might be used to hold explosions. Radio Flying Squads and High Radio Flying Squad vehicles have been pressed into service.