The confirmed death toll passed the 22,000 mark, according to the Kerman governorate in the disaster zone. But an official of the provincial government later said the final toll was expected to rise to more than 30,000 dead.

Interior Minister Abdolvahed Mussavi Lari, quoted on state television, said that "about 15,000 bodies have already been buried," without giving a number for the wounded.

And three people were killed Sunday when an Iranian navy helicopter crashed just outside Bam after delivering aid, the student news agency ISNA reported. The two pilots died along with a third person on board.

So far more than 500 helicopters and planes have delivered aid and ferried the wounded out of Bam since the quake, according to Iranian officials.

And some 11,500 injured survivors have been flown to hospitals around the country for treatment, the interior ministry said.

Charter flights landed at Kerman airport Sunday at a rate of one plane every five minutes, while at Bam airstrip planes were touching down every 15 minutes.

The search for survivors will carry on until rescue teams are certain they can find no more victims alive, interior ministry spokesman Jahanbakhsh Khanjani told AFP.

"So long as there is a chance of finding survivors, these operations will continue," he said. "We will concentrate the operations on places where there is a chance of finding survivors."

The search was expected to have ended Sunday, the UN Office for the Coordination of Humanitarian Affairs said earlier, pointing to the urgent need to rush more international rescue teams to the area.

A UN spokesman in Geneva said that "short of a miracle," there was no expectation of finding many more survivors.

But the state IRNA news agency reported that some 1,000 people had been pulled alive from the ruins Saturday and Sunday.

Those rescued were located thanks to the "sniffer dogs and hi-tech ultrasound equipment of both Iranian and foreign emergency teams", the news agency said.

Since Saturday, mechanical diggers have been bulldozing a former wasteground on the western edge of this pulverised city, burying hundreds in mass graves.

Relatives knelt at the side of the mass graves, some with their hands and heads bowed down in the dust, paralysed in grief over the loss of loved ones.

In the span of just 100 metres (yards), one AFP correspondent saw about 300 to 400 bodies piled up, wrapped in white cloth and blankets, others rolled in carpets.

Most of the dead were adults, but there was one row of babies wrapped in blankets.

The security situation was also deteriorating, with reports of looting in the earthquake zone, and security officials said the Iranian army was planning to set up military checkpoints on the road from Kerman to Bam.

Meanwhile, tens of thousands of people prepared to spend a third night in the open.

On the ground, freezing night-time temperatures and the disorganization of the relief effort in the face of the massive casualty toll left little hope of further survivors being found.

Ari Vakkilainen of Finn Rescues, a Finnish government international rescue organization, told AFP: "I think there are not many people still alive under the rubble because of the way the buildings here are made."

The bricks generally used in Bam buildings are made of baked mud that turn to dust and sand when buildings collapse, which means there are not many air pockets.

Rescue teams from Switzerland, Turkey, Germany, Britain, Italy, Luxembourg, Finland, Azerbaijan, Spain, Ukraine and Poland were among the first to touch down here in response to Iran's calls for international aid.

Iranian President Mohammad Khatami, whose country has waived visa restrictions for relief workers and foreign journalists, said Saturday he would visit Bam and ordered rescue efforts to be speeded up.

IRNA reported that a first US plane bringing aid workers and medical material for rescue operations in Bam, a giant Hercules C-130, arrived at 3 am Sunday (2330 GMT Saturday) in Kerman.

As soon as news broke early Friday of the quake which claimed tens of thousands of lives, US President George W. Bush sent his condolences to the Iranian people and announced aid to the victims.

Shortly afterwards an Iranian official announced that his country would accept aid from all countries except Israel, which Iran does not recognize.

Iran and the United States broke off diplomatic relations after the Islamic revolution in 1979 and the taking of American hostages in the Tehran embassy.

TERRA.WIRE