Besides, suitable air defence measures have been taken to counter possible threats.

'Two choppers would be providing security from air. One would be positioned over Red Fort and the other will keep an eye over the national capital,' an official attached with security measures told IANS.

The home ministry too has asked police to strengthen security at market places, cinema halls, bus and railway stations and iconic buildings in the cities of Delhi, Mumbai and Kolkata.

Patrolling will be intensive in the walled city and snipers will be deployed at all vantage buildings around the 17th century red sandstone fort. Police said vehicular movement will be limited in the area Friday.

Special stress is being laid on anti-sabotage and anti-explosive checks, tight access control and vigil on VIP routes. Quick reaction teams will be in place.