Kolkata, Aug 14 - Security has been heightened at international borders along West Bengal and all districts are on alert ahead of the 63rd Independence Day Saturday.

Vital installations and public places like airports, railway stations and bus stops are under increased vigil, with police and private security agencies doing checking at hotels and shopping malls, said Inspector General of Police (Law and Order) Surajit Kar Purakayastha.

'A large number of plainclothes policemen has been deployed in busy areas and sensitive places,' he told IANS.

He, however, clarified the state has not received report of any 'threat component' from central intelligence agencies.

The exit and entry points to the state capital Kolkata, including the two bridges over river Hooghly, were under close watch, with policemen searching vehicles.

Police pickets have been posted at Metro Railway stations and sensitive areas of the city.