Home Minister Shivraj Patil told reporters after a meeting of the Crisis Management group that Tamil Nadu state was the "worst affected" with possibly over 800 people killed.

In the Andhra Pradesh state, more than 200 people were feared killed, the minister said, and at least 14 people were killed in Kerala state while 14 more died in Andaman and Nicobar Islands.

The minister said the damage due to the tidal waves in Car Nicobar and Greater Andamans was "higher" but details were yet to come in due to snapping of communication links.

In the federally administered territory of Pondicherry not far from Tamil Nadu, at least 102 people were killed, Pondicherry Chief Minister N Rangasamy said.

Andhra Pradesh and Tamil Nadu states are on India's southeastern coast along the Bay of Bengal, hundreds of km from the epicenter.

Patil said coastal areas of West Bengal had also suffered damage and he is likely to visit the affected areas either Sunday evening or Monday.

The minister said thousands of people have been evacuated from the affected areas, and the priority now was to provide relief to the victims including food, medicines and blankets.

Authorities in Tamil Nadu and Andhra Pradesh were carrying out relief and rescue operation on a war footing, the home minister added.

The central government will do all that is necessary to mitigate the suffering of the people and provide relief, he said.

"My heart goes out in sympathy to all those families who have lost their dear ones due to this tragedy," Prime Minister ManmohanSingh said about the tragedy on television.

Tremors lasting less than a minute were felt shortly before 7:00 a.m. and the sea water began rising soon afterwards, washing away beach houses on the Madras coast and crashing onto the road in some parts.

The US Geological Survey early Sunday had revised the magnitudeof an earthquake registered west of the Indonesian island of Sumatra -- the cause of the tsunami, or tidal waves -- upward to 8.9 on the Richter scale.