Iran's interior minister today confirmed more than 20,000 people were killed in Friday's earthquake in the city of Bam.
Foreign rescue workers warned hopes were fading for any more survivors from the disaster which now ranks as the world's most lethal earthquake in at least 10 years.
Iranian state television said 13,000 bodies had been recovered so far.
States across the globe have responded to Iran's appeals, sending rescue workers, doctors, tents and cash to help with the rescue operation.
Cemeteries in Bam were overflowing with fully clothed corpses and hundreds of bodies had been tipped into trenches hollowed out by mechanical diggers, witnesses said.
The pre-dawn quake on Friday also injured about 30,000 people when it flattened about 70 per cent of the mostly mud-brick buildings in the ancient Silk Road city.
Bam airport was converted into a sprawling, makeshift hospital and rubble-strewn pavements were lined with injured, some on intravenous drips.
"The number of dead could be far more than 20,000 - many places are untouched. We are beginning to smell the stench of death. If we haven't cleared the area by the end of the week there will be a threat of epidemics," said one aid worker.
Witnesses saw some looting when vans of young men armed with pistols and Kalashnikovs drove into Bam and stole Red Crescent tents, while others on motorbikes chased aid trucks, picking up blankets thrown out by soldiers.
President Mohammad Khatami said Iran could not cope on its own, as authorities battled to accommodate thousands of homeless people on a second bitterly cold night.
"Everyone is doing their best to help, but the disaster is so huge that I believe no matter how much is done we cannot meet the people's expectations," Mr Khatami said on state television.
The Interior Ministry confirmed yesterday the death toll stood at 20,000, but the chaos and scale of the disaster made it difficult for officials to produce exact casualty figures.
Interior Minister Mr Abdolvahed Mousavi-Lari said he could not make any forecasts about the final toll.
But he said: "In a city of something under 100,000 people, 70 per cent of buildings collapsed... With this scale of damage, the number of dead and injured will be very high."
Officials said many survivors should have been in tents by late yesterday, but witnesses said a number spent the night in the open among palm groves around Bam, burning cardboard and any other material they could find to fend off the cold.
The quake measured 6.3 on the Richter scale and struck early on Friday when many people were at home asleep in Bam, some 1,000 km (600 miles) southeast of the capital Tehran.