Over 3,000 people have been confirmed dead in Andaman and Nicobar islands, ravaged by the killer tsunami waves on Sunday.
The worst hit Car Nicobar and the Nancowrie group of islands are till inaccessible.
The tidal waves were triggered by a massive earthquake off the cost of Indonesia.
Deaths: 2,780 in TN | 120 in Kerala | 73 in AP
"More than 3000 people have been killed, it is now confirmed...and the casualties may go up," IGP, Andaman and
Nicobar Islands, S B Deol told PTI.
"The situation is so bad that the rescue teams have not yet reached Car Nicobar and the Nancowrie group of islands," he said.
Car Nicobar has a population of around 19,000 and Nancowrie nearly 18,000, he added.
Powerful aftershocks measuring six on the Richter Scale rocked the islands in the Bay of Bengal again on Monday at around 06:20 am.
Also see: 'India not prepared to tackle tsunamis'
"You can imagine the situation as the islands are spread over 800 km....the toll will be much higher. We are very apprehensive as we do not know what has happened in Nancowrie group of islands at all," Deol said.