The alert has been sounded from January 20 to January 27.

According to sources in the state home ministry, central intelligence agencies have passed on inputs that Lashkar-oToiba operatives will to move in from Bangladesh through Malda.

“There were inputs that 20-25 LeT operatives may sneak into India before the Republic Day. We are not taking any chances and maintaining a strict vigil on the border,” said Prabhat Singh Tomar, BSF DIG of Malda range.

A similar alert was issued on November 15 last year after inputs from Delhi that “six to 10” Indian Mujahideen (IM) cadres were set to enter Kolkata from Bangladesh one by one and then regroup before carrying out attacks anytime between November 15 and 30.

“There is no specific threat perception this time. It is a general alert after we came to know that there is a possibility of a terror attack or a bomb blast in the state, especially in North Bengal,” said a senior home ministry official.

The city and state police have already stepped up vigil in New Market, Chowringhee, Gariahat, Park Circus, Victoria Memorial, Alipore Zoo and other public places, which seen a heavy crowd.

The Commissioner of Kolkata police, Gautam Mohan Chakrabarty, admitted “Kolkata may be targeted by terrorists attack and NGOs should come forward to make people aware of safety measures”.