Media reports suggest that the intelligence inputs warn of possible attacks on Mumbai, Calcutta, Bangalore and the coast of Gujarat.
Inputs inform that the attacks may be large scale and similar to that of the Nov 2008 Mumbai terror attack.
Apart from the indication a sea-based attack, no other details on the intelligence inputs have been revealed.
The security has been beefed up in the regions under the threat with local police and the coastal security on high alert.
This comes weeks after the Federal Bureau of Investigation (FBI) foiled a 26/11-like terror plot wherein a Pakistan-based terror outfit, Lashkar-e-Toiba was planning an attack using an American.