At least 6,866 people are now known to have died with another 30,000 injured.

The UN deputy spokesman Manoel de Almeida e Silva said that an estimated 33,000 more were believed to be still buried under the rubble.

The death toll rose by more than 2,000 in the first few hours after dawn. And it is expected to continue climbing as hopes fade for the thousands still missing.

The BBC's Paul Adams reports: "Help, badly needed, has now arrived"

The scale of economic damage has also begun to emerge. The business association, Tusiad, said the quake could cost the struggling economy $40bn.

And there are fears of major environmental damage as firefighters continue to tackle an inferno at the country's biggest oil refinery. Officials say it could take until Saturday to extinguish the fire.

Battered streets have been deserted

Thousands of Turks spent a second night camped outside fearing their damaged homes could collapse or because they had no homes to go to.

Prime Minister Bulent Ecevit announced on Thursday that tent cities were being set up. Additional housing will be available at a camp recently used for Kosovan refugees.

He said the state would also bury all bodies, not yet claimed by families, for public health reasons.

The prime minister acknowledged the mounting public criticism over handling of rescue efforts, but said the state had mobilised all its resources.

(Click here to see a map of where the earthquake struck)

Fresh rescue teams arrived from abroad overnight to continue searching for more than 10,000 people still missing.

The fear of aftershocks kept residents out of their homes

But doctors have warned they do not expect people buried in rubble to survive for more than three days without water.

Many victims, trapped under collapsed buildings, have already died in the intense summer heat even as rescuers were digging towards them.

Rescue workers, removing contorted bodies from the rubble, are wearing scarves over their faces to keep out the growing stench of rotting flesh.

Exchange students who were in Turkey when the quake happened explain what they saw

The area was shaken yet again on Thursday by three aftershocks, all measuring 4.0 or more on the Richter scale, the Kandilli seismological institute in Istanbul reported.

The aftershocks came as the head of the chief of Turkey's main earthquake observatory that the public should be on alert for further seismic activity.

Shock turns to anger

Survivors are now turning their anger on the Turkish Government - accusing it of not moving swiftly enough to meet the crisis - and on corrupt builders responsible for putting up sub-standard housing.

The BBC's Rageh Omaar reports: "Now comes the battle to find food and shelter"

Despite the aid pouring in from abroad, many people say they have been left to hunt for missing relatives in the rubble using their bare hands.

"When are they going to come and help us? When we are all dead?" cried Zeyfettin Kus, standing in front of a collapsed block of flats in Izmit where three neighbours were buried.

Ayse Mutlu, holding a vigil for her newly-wed daughter who was thought to have died, has sat on a chair in front of her toppled building ever since the quake.

''I'm not leaving until they find her,'' she said.

Desperation

Dwindling food supplies on top of power and water shortages have added to the mood of desperation.

Crowds mobbed a convoy of bread trucks that entered Izmit, where around 76,000 buildings are estimated to have come down.

The authorities in the city have been forced to use the town's ice-rink as a morgue.

Rows of bodies wrapped in blankets and towels have been laid out, awaiting identification.

Shoddy construction

There has been growing anger that so many buildings fell down because no precautions against earthquakes had been taken.

The BBC's Jonathan Beale: "Everybody is living in the street"

In Yalova, one of the city's biggest contractors narrowly escaped a lynching by an angry mob accusing him of shoddy construction practices. His car was set ablaze.

"Murderers !" was the stark headline on Wednesday's daily newspaper Hurriyet.

In recent years, officials have turned a blind eye to contractors who have skimped on materials to provide housing for a flood of rural migrants.

Oil fire raging

The prime minister said the ''most dangerous problem'' was the fire raging at Turkey's biggest oil refinery near Izmit.

Firefighters struggling to contain oil refinery fire

The damage threatens severe setbacks to an area that accounts for a third of the country's economic output.

Reports said 100,000 tons of water and chemical foam had been dumped on the refinery, in an attempt to extinguish the blaze.

There have been fears that the flames could engulf all 30 storage tanks - and a nearby fertiliser factory with 8,000 tons of dangerous ammonia - touching off an environmental disaster.

But the prime minister said only two of the tanks were still burning.

Barriers have been set up to stop the oil spilling into the sea.

Foreign aid

The quake, which measured 7.4 on the Richter scale has caused destruction from Istanbul to the port of Golcuk about 130km (80 miles) away, where up to 10,000 people are believed to be trapped.

A massive international rescue operation has swung into operation with Britain, Greece, Israel, Switzerland, France, the US, Germany, Russia and Japan, among those offering assistance.

Seven affected provinces have been declared a disaster zone. The government has also promised compensation to victims of the quake.

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