Britain's contribution to relief efforts in earthquake-hit Indonesia was held up today after an aircraft carrying UK search and rescue experts developed a fault.
Sixty firefighters from around England were due to fly to the island of Sumatra this morning but they were grounded at Gatwick Airport when their plane suffered mechanical failure.
An emergency response team from the Department for International Development (Dfid), which chartered the flight, was also delayed.
The setback frustrated British officials but they said they were looking at how they could get the experts to Sumatra as soon as possible.
A Government source said: "There has been a delay due to mechanical failure but it remains the firm intention of everybody to get them in the air, hopefully by the end of today."
The official death toll from Wednesday's earthquake, which measured 7.6 on the Richter scale, stood at 715 today but the United Nations warned it could be as high as 1,100.
Worst affected was the city of Padang on the western coast of Sumatra, where hundreds of buildings including two hospitals and a shopping mall collapsed after the massive tremor.
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."
Ten volunteers from the civilian International Rescue Corps, based in Grangemouth, Scotland, are flying out to Sumatra today after being asked for help by the Indonesian government.
They will take specialist equipment including listening devices and thermal cameras which can detect trapped survivors.
Martin Hatfull, the UK's ambassador to Indonesia, said there were no reports of British casualties in the disaster.
The UN's humanitarian chief, John Holmes, said the latest figures suggested the death toll had already risen to 1,100.
He said he feared thousands more were trapped in the rubble of homes, hotels, hospitals and schools destroyed or badly damaged.
Indonesian president Susilo Bambang Yudhoyono warned people to be "prepared for the worst" as the full horror 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.
There were fresh hopes that survivors could be found after rescuers pulled a 19-year-old student from the rubble of her college alive this morning, 40 hours after the earthquake struck.
But Indonesian officials warned that a shortage of heavy digging equipment was hampering efforts to clear collapsed buildings.
Geologists said the Sumatran tremor was not related to the other deadly quake that hit islands in the South Pacific on Tuesday.
Earlier this week, floods crushed homes in nearby Cambodia and Vietnam and submerged much of the Philippine capital Manila, killing more than 330 people.