High alert notice has been issued in the eastern Indian city Kolkata after the Ministry of Home Affairs Thursday issued a terror alert for the metropolis, said police.

The specific alert, based on intelligence inputs, has been sent to the West Bengal Police.

The possible targets of attack are the Subash Chandra Bose International Airport, Kalighat Kali Mandir and 24 Parganas, according to police.

"We have certain inputs about terrorists trying to take some kind of action here. We are working on it and getting up to meet this threat," state Director General of Police Bhupinder Singh said.

The police official refused to reveal the exact nature of the threat and the terrorist organisation behind the plan.

But another police official said the alert is about the heightened activity of sleeper cells of some terrorists groups in Kolkata.

"We have received inputs that the Indian Mujaheedin is planning to do something. We can't say anything more on this at this moment, " said the official on condition of anonymity.

Security has also tightened up for nearly one week in the Indian capital New Delhi after some Western countries issued travel advisory warning of terrorist attack there.

The Indian Mujaheedin is a home-grown militant group blamed for a number of terrorist attacks in the country in the past few years.