Intensified anti-sabotage and vehicular checks were being held across the city as part of enhanced security arrangements. About 5500 police personnel have been deployed for security at Fort St George where Chief Minister Jayalalithaa will unfurl the national flag.
Also, 12,000 more personnel drawn from wings, including the Armed Reserve, have been posted at all key locations including vital installations.
Snipers have been positioned at several "vantage positions" that would witness VVIP movement on the day and screening of air, train and bus passengers were being done, police added.
Vigil has been enhanced in the coastline and on the highways leading to the city as part of security arrangements.