Relief efforts will aim to deliver clean water supplies and shelter
British search and rescue experts are preparing to fly to Indonesia to offer help after a massive earthquake.
The Department for International Development (DfID) team was due to depart from London 24 hours earlier but was delayed by technical problems.
The plane to the city of Padang will carry UK aid agency staff and rescue equipment including plastic sheeting, medical and water purifying equipment.
The quake killed at least 1,100 people when it struck Sumatra on Wednesday.
A tsunami in the South Pacific on Tuesday has also prompted UK agencies to prepare aid efforts.
Rescue workers in the Samoan islands and Tonga continue to search for survivors of the tsunami, which was triggered by an 8.3-magnitude earthquake and killed at least 149 people.
The search and rescue team bound for Indonesia is made up of 65 firefighters includes personnel from the West Midlands, Hampshire, Leicestershire, Cheshire, Greater Manchester, Lancashire, Kent, Essex, West Sussex and Wales.
They will be accompanied by humanitarian experts from DfID.
Their departure to Padang was delayed after their aircraft developed a fault.
But following what a DfID spokesman called "a day of intense activity searching for an alternative aircraft", a C17 military transport aeroplane was located which is expected to leave from RAF Brize Norton on Friday night.
The spokesman added: "A DfID humanitarian adviser is already in Padang helping the UN coordinate search and rescue efforts.
"An extra two-person DfID team is en route to Jakarta to liaise with the Indonesian authorities and other donors on the relief effort."
International Development Secretary Douglas Alexander said: "Thousands of people are still trapped under the rubble in Padang and their hopes of survival decrease the longer they remain.
"The UK's fire and rescue experts will help provide a lifeline. In addition, we stand ready to assist the government of Indonesia and are in regular contact with the Indonesian authorities, other donors and agencies in Jakarta."
He said the operation was being well co-ordinated by the UN, and added that Britain was already in talks with the Indonesian government about the long-term recovery and rehabilitation of the area.
"This is a huge humanitarian issue but it's also going to be a huge recovery issue as well," he told the BBC's Today programme.
Meanwhile, 10 volunteers from the International Rescue Corps, based in Grangemouth, Stirlingshire, are preparing to fly out to Sumatra after being asked for help by the Indonesian government after the 7.6-magnitude quake.
They will take specialist equipment including listening devices and camera systems which can penetrate rubble to search for trapped survivors in collapsed buildings.
Gloucester-based search and rescue specialist Rapid-UK has already sent a 16-person team of rescuers and medics to the area.
Oxfam is sending an emergency response team to Padang, the capital of West Sumatra province.
The team will join staff from the charity's local partners who are distributing shelter tarpaulins, hygiene kits and clothes.
Mechanical diggers to clear routes affected by mudslides and other debris are also being sent in.
The quake brought down hospitals, schools and shopping malls, cut power lines and triggered landslides.
A second, weaker quake of 6.8 magnitude struck on Thursday but there were no immediate reports of further casualties or damage.
Rescuers are trying to find survivors buried in the rubble
Jane Cocking, Oxfam's humanitarian director, called for "the support of the British public to help us save lives in this grave tragedy".
The earthquakes came in the wake of Typhoon Ketsana which swept through the Philippines, Vietnam and Cambodia at the end of September.
It has flooded millions of homes and killed hundreds of people across the region.
Oxfam is providing water and blankets, clothes and cleaning equipment in the Philippines as well as small cash grants.
Food, household items and water supplies are going to Vietnam.
Emergency supplies and a team of staff are on the way to help victims of the tsunami in Samoa and Tonga.