Teams of volunteers are scrabbling through mountains of rubble for some of the estimated 10,000 people still reported missing more than 48 hours after the quake, which measured 6.7 on the Richter scale.

The official death toll has now risen to more than 4,000, with a further 18,000 reported injured.

Hi-tech equipment

A second search and rescue team, dispatched from Britain with two sniffer dogs, was due to begin work on Thursday as part of the international relief effort.

The group of 30 firefighters, drawn from fire brigades in Kent, the West Midlands, Essex, West Sussex and Hampshire, flew out from RAF Lyneham in Wiltshire to Istanbul.

Andy Beale, from Essex Fire Service, said: "Our team is very experienced - we have been to Macedonia and Rwanda."

Divisional officer Peter Pearce, from Kent Fire Brigade, said: "We have fibraphone listening equipment and thermal imaging equipment to help the existing rescue effort.

"Because the disaster is so large co-ordination will be one of the biggest difficulties."

Dr Iain McNeil, from West Sussex Fire Brigade, added: "This is the first time I have been to an earthquake situation, particularly on this scale, and I am a little nervous."

Testing conditions

They will boost a team of 27 British firefighters and 13 members of the International Rescue Corps already working in one of the worst hit areas, east of Izmit.

This wrecked building in Izmit is viewed from a helicopter

Stephen Coles, a spokesman for the IRC, said the advance team had already set up a preliminary base camp in Duzce.

"It is extremely hot out there and it is going to make conditions very difficult not only for the casualties but for the rescue workers. It means dehydration will become an issue," he said.

On Wednesday the team worked on a collapsed five-storey building where they removed five people, of whom all but one were dead.

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.

Teeneager's lucky escape

British teenager Robert Hicks, who was staying in a house in Izmit which collapsed, managed to escape unhurt.

Robert, 17, who lives in Manchester and is head boy at Hulme Grammar School, in Oldham, was one of three teenagers on an exchange visit.

All three were due to return home later on Thursday.

His mother, Karen Siddall, said: "I am just relieved to know that he is OK. It has been a nightmare and I can't wait for him to come home.

"I'd spoken to Robert about three hours before the earthquake hit and obviously there was no sign of anything being wrong.

"He said he'd been having a wonderful time and was planning a day by the pool and shopping before preparing to come home."

Fundraising appeal

The International Red Cross has launched an initial appeal for £4.4m to assist the relief programme.

The European Union has said it was sending £1.3m in immediate humanitarian aid, and promised to give more.

Britain has donated £512,000, Germany provided £358,000, and Ireland added £175,000.

The development agency Muslim Aid, based in London, announced it was opening an appeal for the victims and was sending an initial donation of £50,000.