More than 10,000 people have died in the disaster, but with many more still missing the rescue teams are working around the clock in difficult and dangerous conditions.

Temperatures in Turkey, which have reached 100F on some days, mean the rescue workers are having to combat dehydration and exhaustion.

Gary O'Shea, Assistant Operations Director for the International Rescue Corps, said the heat is also speeding the decomposure of bodies trapped in the rubble, which will become a health hazard if they are not retrieved soon.

UK rescuers 'highly trained'

The earthquake, which struck in the early hours of Tuesday, was one of the century's strongest, and left an arc of destruction from Istanbul to the Golcuk area, about 80 miles to the south-east. It measured 7.4 on the Richter scale.

The UK has sent between 60 and 70 people to help the aid effort, including members of the International Rescue Corps and rescue organisation Rapid UK.

Thirty firefighters, drawn from fire brigades in Kent, the West Midlands, Essex, West Sussex and Hampshire, flew out to Istanbul on Thursday.

So far UK rescue teams have recovered two people alive and four bodies, from Adapazari, at the epicentre of the earthquake, and from Duzce, 150 east of Izmet, which was also at the centre of the disaster.

The rescuers are highly trained, having completed two years' training, Mr O'Shea said.

A member of Israeli rescue team climbs out of ruins in Golcuk

It includes operating a Trapped Person Locator, which can detect vibrations through buildings, as well as thermal imaging equipment and satellite communication systems.

The IRC has completed search-and-rescue work in Iran, Rwanda, Liberia and Armenia. Mr O'Shea stressed the importance of international aid to a country in distress.

"As well as providing invaluable help, it provides psychological healing to those in the country affected, by showing that the global community cares," he said.

But the job is not without its hazards, which, apart from the heat, include moving inside unstable buildings.

"You wouldn't crawl through a building site, but that is what our rescue workers are doing daily," he said.

'Trauma of finding bodies'

As they search through mountains of rubble, there is also the risk of further tremors, which could demolish the buildings' remains with the rescuers still inside.

Mr O'Shea said hopes of finding people are dimming, as after 48 hours it becomes more and more difficult for trapped people to survive.

"There are still miracles, though," he said.

He said the reward of finding survivors is tempered by the trauma of having to remove bodies, which is "very taxing for the rescue teams".

"It affects them emotionally," he said. "The psychological trauma is very great.

"But it is often not until people return home that it really hits them."