The killer tsunamis triggered by a massive earthquake in Indonesia on Sunday, the worst in four decades, battered a huge swathe of south Asia, killing some 24,000 people, including some 7,000 in south India.

Massive waves crashed into villages along a wide stretch of the Sri Lankan coast killing at least 12,000 people and displacing a million others.

Two Indian nationals were among the nearly 840 people killed and thousands injured by the tsunami in Thailand, officials said on Monday.

• India caught unawares | Pictures | More reports on the tragedy

Some 4,700 people in Indonesia, whose Sumatra Island was the epicentre of the quake measuring 8.9
on the Richter Scale on Sunday, perished as the tidal waves razed the coasts of these two countries as also Thailand, Malaysia and the Maldives.

• 2000 confirmed dead in Andamans | 'Quakes don't kill, human error does'

Andaman and Nicobar, closest to Sumatra coast, the epicentre of the quake, was also badly hit, accounting for 3,000 deaths, including air force personnel and their family members.

Pope John Paul II lent his moral voice to calls for the international community to help.

The International Red Cross in Geneva issued an initial appeal for donations of $6.7 mn in cash, relief goods or services for the next six months.

"Thousands have already died because of the flooding, but unless there is a rapid response to the emergency, many more people could die in the coming days," said Jasmine Whitbread, international director of the aid group Oxfam.

"The flood waters will have contaminated drinking water and food will be scarce."

Said David Alexander, international director of the British Red Cross, "We are in for a big emergency disaster response, and we will be at it for many months to come."

The United Nations is sending special teams to countries hit by the killer quake and the tsunami waves, even as all UN offices in the quake-hit region have been mobilised to support relief efforts.

"UN disaster assessment and coordination teams are being dispatched throughout the region to work with the governments of affected countries in providing rescue and relief assistance," said a spokesman of the UN Secretary General.

The first teams were sent to Sri Lanka, the worst hit nation by the tidal waves, said the UN office for the Coordiantion of Humanitarian Affairs.

"This is the first step in what will surely be a larger UN response to catastrophic losses suffered by earthquake and tidal waves," said Jan Egeland, the UN Emergency Relief Coordinator.

Emergency supplies are on stand-by at the agencies global supply hub in Copenhagen and relief flights are expected to be launched at any hour, the world body said.