Police said 3,000 people were confirmed dead and another 2,000 presumed killed in the remote Andaman and Nicobar islands in the far east, where contact has still not been made with isolated communities of thousands of people.
Hundreds of thousands are homeless. The high number of missing means India’s toll was likely to go much higher, interior minister Shivraj Patil said.
“The situation is quite grim and while we cannot bring back those who have lost their lives, we can and must surely try and help those who have survived,” said Mr Patil.
Contact has still not been made with thousands of people on two islands in the Andaman and Nicobar islands, home to some of India’s most primitive tribes and close to the epicentre of the magnitude 9.0 quake.
“There are 3,000 people in each island. We have not been able to raise wireless contact with these islands,” said chief secretary VV Bhat from Port Blair, capital of the federally-administered chain of 572 islands.
“The worst-affected islands are Car Nicobar and Great Nicobar (islands) which were totally cut off due to extensive inundation,” the government said.
In Car Nicobar in the Andaman and Nicobar islands, an air force base was severely damaged, with houses and apartment blocks razed by the tsunami. Dozens of air force personnel and their families are dead.
The overall toll on the island is 500 and rising.
“There are hundreds and hundreds of people missing. The damage is colossal,” said Indian Air Force spokesman Mahesh Upasani.
Nothing has been heard since Sunday from Great Nicobar island further south and closest to the epicentre. The Andamans and Nicobars have been hit by several moderate aftershocks.
Villagers sought the help of soldiers to find bodies of missing relatives as the number of dead rose to 3,670 in the worst-hit state of Tamil Nadu, on the Indian mainland.
Most of the dead are women and children from poor fishing families.
Whole fishing villages have been wiped out.
“I don’t think my boy and girl would have made it through this havoc,” said Kolanda Velu, a resident of Cuddalore, one of the worst-hit districts of Tamil Nadu, about 170km south of Madras.
“But I hope and pray that we can at least find their bodies so that we can see them one last time and give them a decent burial,” he said, fighting back tears outside a makeshift government shelter.
Police said 435 were missing in the state and almost 1,200 had been hospitalised. About 50 people were killed in houses around a nuclear power plant in Tamil Nadu after waters swept away a wall.
The plant, on the coast at Kalpakkam, was shut down after seawater entered a pump house supplying coolant to the turbines.
But company officials said there was no danger of a radiation spill.
Prime Minister Manmohan Singh put off a visit to devastated areas, fearing the trip could disrupt relief work.
But Sonia Gandhi, the Italian-born chief of the ruling Congress party, was expected to inspect the damage.
The Indian government has said the cost of damage would not be known for at least a week.
The cabinet has allocated five billion rupees (e85 million) for relief and rebuilding so far.