Sources said following instructions from the Centre, a seven-tier security arrangement was put in place at the airport. Passengers with valid tickets were alone allowed entry after their baggages were thoroughly frisked.

CISF personnel were taking all precautions and heightened vigil at the airport, including at the parking lots. Entry of visitors have been banned and it would be in force till August 22, the sources said.

Meanwhile, about 20,000 personnel were deployed on security duty in Chennai city, with armed police keeping guard at all vital installations.

Police sources said over one lakh policemen have been deployed on security across the State.

Patrolling and vehicle checks were intensified and lodges and hotels were being searched to identity any anti-social elements staying there.

Temporary check posts were set up at vital points to track entry and exit of vehicles to the city.

Barricades have been erected in various parts of the city as part of intensifying the vehicle checks and all vehicles entering the city were subjected to thorough checks. Habitual offenders have been detained as a precautionary measure and night patrol was also stepped up.

Following a communique from the Union Home Ministry that anti-social elements might disturb the Independence Day celebrations, all airports, bus terminals, railway stations and other important destinations were put on high alert.

Police have also intensified vigil at all important places like temples, places of worship, commercial establishments, shopping malls, amusement parks, where public would throng in large numbers. The police have also instructed the public to alert the local station if they found any one moving under suspicious manner. Security was also beefed up in all railway stations. Apart from police personnel in uniform, those in plain clothes were also deployed on security duty.