Three weeks short of the first anniversary of 26/11 attack, is another Mumbai-type attack imminent? Officials warn that it is, and the attack could once again come from the sea.

The Home Ministry says there are fresh inputs warning of a similar terror attack, and this time the targets could be cities of Kolkata, Mumbai and possibly Bangalore.

Adding weight to the alert are the rare public warning by key ministers in the last couple of days.

"I've been warning Pakistan every time, to not play with us again and to stop with the Mumbai game. I'm warning Pakistan for the last time. If Pakistan attempts to send terrorists into India again, India will not only foil those attempts but also give them a crushing response," Home Minister P Chidambaram had said at a public meeting on Sunday.

On Monday, Defence Minister A K Antony highlighted the presence of terrorist camps across the border.

"Large number of terrorists camps are operating across border. Unless serious and sincere efforts are made to control the terrorists it is very difficult to improve relations. Even now, there is continuous effort to push trained terrorists to J and K and India. It is a serious matter for concern for us," Defence Minister A K Antony said.

The government has issued a nationwide alert against such an attack in coming weeks. It is basing this alert on a wide variety of inputs, from a spurt in infiltration in Kashmir to the arrest of an American, David Headley, in Chicago.

The FBI say he was plotting to attack India and Denmark. Headley's communication with the Lashkar-e-Toiba (LeT) has sent alarm bells ringing in India and the US.

Home Ministry sources, however, say that Indian agencies are ready with counter measures, even retaliation to tackle any attack.