OXFAM, the Oxford-based aid agency, is preparing to ship 25,000 food parcels to Sri Lanka following the earthquake that caused a tidal wave to swamp large parts of Asia, killing thousands.

Phil Esmonde, Oxford resident and head of Oxfam in Sri Lanka said: "This is a massive humanitarian disaster and communications are so bad we still don't know the full scale of it.

"Unless we get aid quickly to the people, many more could die."

The charity has already sent 60 huge water tanks to Trincomalee, where many wells have been contaminated by flooding, and is preparing 25,000 parcels of rice, flour, dhal, fish, sugar and cereal. Flood relief experts are also on their way.

Spokesman Brendan Cox said: "Oxfam will be leading a major response and it's likely we'll be sending aid from our Bicester warehouse in the coming week.

"We've been working there for over 10 years, we've had a long-term development programme and recently we've been dealing with other floods in the east of the country."

Mr Esmonde added: "Food, water and shelter are all urgently needed by the people affected. We have already started getting aid to the people -- but much more will be needed. Without a rapid response those who survived the flooding could still fall victim to disease or dehydration."

THE earthquake behind the tidal wave was caused by one of the plates which makes up the world's surface moving a matter of metres, experts said.

The epicentre of the quake, which measured 8.9 on the Richter Scale, was off the west coast of the Indonesian island of Sumatra.

Dr Roger Musson, a seismologist with the British Geological Survey in Edinburgh, said the fault line running under the Indian Ocean was 1,200km long, 500km wide, in three sections, and that it had moved just 15 metres.

He added: "This will happen again in the future over the next several million years and has been happening for several million years in the past."

He said the fault under the Indian Ocean was much bigger than the San Andreas fault in California.

His colleague Dr David Booth said earlier: "The earth displacement associated with this earthquake has generated a Tsunami, a tidal wave.

Dr Booth said he was aware of a warning system in the Pacific but not of any similar system around the Indian Ocean.

The earthquake is thought to be the largest since 1964.