A major rescue operation was under way today after a second powerful earthquake hit the Indonesian island of Sumatra, killing hundreds and leaving thousands trapped in rubble.
Officials said the confirmed death toll had passed 500 after the latest 6.8-magnitude quake - about 180 miles from the epicentre of the more powerful tremor at sea yesterday.
Hundreds of buildings in the Sumatran city of Padang collapsed after yesterday's 7.6 magnitude quake, including two hospitals, a shopping mall and mosques. Several landslides were also reported nearer the coast.
Indonesian president Susilo Bambang Yudhoyono warned people to be "prepared for the worst" as the scale of the tragedy unfolded.
"Let's not underestimate (the disaster). Let's be prepared for the worst. We will do everything we can to help the victims," he said.
Martin Hatfull, British ambassador to Indonesia, said there were no reports of British casualties.
At least 500 buildings in Padang collapsed or were badly damaged in the first quake.
The US Geological Survey said today's tremor hit about 150 miles south of Padang. It damaged 1,100 buildings, including mosques and homes, in Jambi.
In heavy rain overnight, Padang residents fought fires with buckets of water and used their bare hands to search for survivors, pulling at the wreckage and tossing it away piece by piece.
Health minister Siti Fadilah Supari confirmed that two hospitals and a mall collapsed in the city.
British aid was being sent today to areas of the country affected.
Stocks of emergency shelters, hygiene kits and clothing are ready to be distributed by aid teams funded by British charity Oxfam once workers can get through to the worst-affected places.
And the British Red Cross has launched a fundraising appeal to help those caught up in both the earthquake and the tsunami.
Mr Hatfull said British officials were being sent to the island today.
"At this stage, we don't have any information of any British casualties," he said. "We've been working to find out where Britons might have been staying and have also been checking with the authorities and hospitals.
"We know two Britons were in the area but they are, by all accounts, OK."
He said it was unknown how many UK citizens were in the area at the time.
"We think it's quite likely there were a few Britons there but it's not a major tourist destination," he said.
He said it was clearly "a very major and devastating earthquake".
"I have spoken to someone out there and the picture she painted was one of severe devastation," he added.
"Most buildings of two storeys and higher have collapsed or been severely damaged. Single-storey buildings are also severely damaged."
The UK Government said it was ready to help and was preparing to send assistance.
"The Department for International Development is closely monitoring the situation in Indonesia," said a spokesman for the department.
"We stand ready to assist with any specific requests from the government of Indonesia and are meeting with the Indonesian authorities, other donors and agencies in Jakarta this morning to discuss the needs.
"We are also preparing to send an expert humanitarian assessment team to Indonesia and are ready to mobilise the UK Fire and Rescue Service if called upon."
At least 80 people were missing at the five-storey Ambacang Hotel in central Padang. Rescuers, working in heavy rain, found two survivors and nine bodies in the rubble.
Indonesia sits on a major geological fault zone and is regularly hit by earthquakes. The latest were along the same fault line that led to the 2004 Asian tsunami that killed 230,000 people.
Geologists said the Indonesia quakes were not related to the other deadly quake that hit islands in the South Pacific on Tuesday.