Aid agencies have launched a massive humanitarian relief effort in Asia after catastrophic sea surges killed thousands following an ocean bed earthquake.

Governments have also moved to help the millions of people who have been left homeless after a series of tsunamis battered the region.

The first flight carrying British Government assistance for victims in Sri Lanka left the UK yesterday afternoon, carrying 250 tents and 5,000 plastic sheets, in response to a request for help from the Colombo government.

International Development Secretary Hilary Benn said the Government had already given £400,000 through the EU to the first Red Cross appeal to help survivors, and was providing about £50,000 to the World Health Organisation to prevent outbreaks of disease.

Two officials of the Department for International Development (DFID) were in the region as part of a United Nations disaster assessment team determining what kinds of help were most urgently needed.

A three-person DFID assessment team has already been dispatched to Sri Lanka, while two officials were on stand-by to fly to the Maldives.

Extra personnel from a number of British aid agencies have also been arriving in the earthquake-hit region to assist with the humanitarian effort.

Save the Children UK said it was continuing to scale up its response to the aftermath of the earthquake and had launched a global emergency appeal for the children affected.

Toby Porter, director of emergencies at the charity, said: "Our priorities at the present time are to get as many children as we can to safety, under shelter, re-united with their families and with enough to eat and drink."

Existing country teams are assessing the situation in Sri Lanka, Thailand, India, Indonesia and Myanmar while emergency personnel are arriving in the region.

The charity has begun handing out dried food to 33,000 families in Sri Lanka with the help of £490,000 of funding provided by the Norwegian Ministry of Foreign Affairs.

Save the Children is also planning to hand out non-food items including sheets, candles and detergent.

Cafod, part of the Caritas network, said the international catholic agencies have pledged £1.1m to cover immediate needs.

The network will be sending emergency workers to Sri Lanka, India and Indonesia to assess needs and organise the relief response, which will include shelters and medicine.

Oxfam has started distributing sleeping mats, plastic sheeting and food to thousands of homeless families in Sri Lanka.

The agency has sent sixty 1,000-litre water tanks to Trincomalee, one of the worst affect areas

The charity has launched an appeal for public donations to assist with the disaster, and is carrying out assessments of the situation in Tamil Nadu and Indonesia.

In India, World Vision said the first concern was feeding survivors of the tsunamis.

"We are providing cooked food so that people have sustenance and we expect to feed 5,000 families today on the east coast," said communications manager Jayath Vincent.

"We are also moving into the supply of dried food, such as rice and dhal, as well as blankets so that people have at least something to start with when they go back."

World Vision's relief director in Sri Lanka, Andrew Sundersing, said that the charity was running feeding programmes in eight districts and would be launching more today.

A team of three British Red Cross logistics experts left last night for Sri Lanka to prepare for the arrival of a Red Cross charter plane full of equipment, which should be leaving from Bristol airport today or tomorrow.

Many organisations were warning last night that survivors would be at risk from outbreaks of disease as dead bodies and flood water contaminated the water supply.

The International Federation of Red Cross and Red Crescent Societies has included enough medicine to treat 2,000 cases of diarrhoea disease in an initial shipment of relief supplies which left Denmark for Sri Lanka yesterday.

Nick Young, chief executive of the British Red Cross, warned that conflicts in parts of Sri Lanka and Aceh in Indonesia were going to make the aid effort harder.

"Conflict areas tend to be areas which are more needy, where basic health care and basic structures don't work, and where access is difficult.

"I think this is going to be with us for a long time," he added.

* To donate to the emergency appeals, people can call any of the numbers below:

The British Red Cross: 0870 512 5125

Cafod: 0500 858 8885

Oxfam: 0870 333 2500

Save the Children: 0207 012 6400

World Vision: 0800 088 088