In the wake of the terrorist attack on the Pathankot Air Force Base, security was on Saturday stepped up in the national capital and several states. Security has been beefed up at the airport, railway stations, bus stands and other vital installations.

A senior police official said vigil has also been heightened in several areas, including popular marketplaces, in South and Central Delhi and VIP movement zones in Lutyen's Delhi, with the special police commissioner (Law and Order) taking stock of the situation.

The official said sleuths of the crime branch and the special cell of the Delhi police have also been roped in, and the security unit has been asked to form a strategy in connection with potential threats to VIPs in the national capital.

The local police have been asked to remain extra vigil and Special Weapons and Tactics team and quick response team have also been deployed in several parts of the city for quick response in cases an emergency situation arises.

In the meantime, Punjab has been put on maximum alert, while security was also tightened in neighbouring Haryana and Chandigarh.

The Himachal Pradesh police have beefed up security in Kangra, Chamba and Una districts, adjoining Punjab. Kandwal, Majra and Danghu areas of Kangra district are close to Pathankot.

Himachal's borders with Punjab and Jammu and Kashmir have been sealed completely after the attack. Besides, additional police forces have been deployed at strategic entry points of Kangra, Chamba and Una districts along the interstate borders to keep vigil on any suspicious movement.

Police patrolling has also been intensified and every vehicle entering in the state from interstate borders is being checked thoroughly.

Several important installations such as hydel power projects and historical temples are situated in Kangra, Chamba and Una districts.