The search for survivors will carry on until rescue teams are certain they can find no more victims alive, an interior ministry spokesman told reporters.
"We will not stop the search operations for survivors. So long as there is a chance of finding survivors, these operations will continue," said Jahanbakhsh Khanjani noting that earthquake survivors had in the past been recovered up to four or five days after the event
"We will concentrate the operations on places where there is a chance of finding survivors," Khanjani added.
The UN had said search efforts would end on Sunday, after a meeting in Bam with local authorities, adding that international rescue teams were no longer needed.
Shortly before the UN's announcement, about 200 people were pulled out of the ruins, reported the state news agency, IRNA. It was the first official indication of the progress of the rescue operation.
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.
But on the ground hopes were fading fast of finding many more survivors in the face of freezing night-time temperatures, over the past 48 hours and the disorganisation of the relief effort in the face of the massive casualty toll.
Iranian officials now say that up to 30,000 people may have died in the powerful earthquake measuring 6.3 on the Richter scale that hit Bam before dawn on Friday.
Roland Schlachter, heading a team of 10 rescuers from the Swiss Corps for Humanitarian Aid, said on Sunday the chances of finding more survivors were extremely low.
"It has to do with the way the houses were built and have collapsed. There appears to be very few air spaces created when the buildings collapsed," he said.
He pleaded for tents and blanket to be sent to the survivors.
The quake was one of the world's
worst in almost 10 years
"The people are practically standing naked in the cold on the streets because they've lost everything they had," he said.
Iran has said it will accept aid from all countries except Israel.
From China to South Africa, Britain to Australia, nations rushed to respond to Tehran's appeals. They sent rescue workers, doctors, tents and cash to help deal with what appeared to be the world's most lethal earthquake in at least a decade.
The first US plane, a Hercules C-130 bringing aid workers and medical material for rescue operations, arrived early on Sunday in Kerman, southeast Iran, reported Iran's official news agency IRNA.
High level US and Iranian officials put aside diplomatic differences spanning more than two decades, to directly discuss humanitarian aid, said a US State Department spokesman on Saturday.
US Deputy Secretary of State Richard Armitage and Iran's permanent representative to the United Nations Muhammad Javad Zarif held telephone talks on aid.
"Given the urgency of the situation we deemed direct contact to be the most appropriate channel," said State Department spokesman Lou Fintor.
The US military said it had sent a transport plane with medical and humanitarian supplies to Iran and would ship about 68 tonnes of aid from logistics sites in the Gulf.
Washington and Tehran broke ties after Americans were held hostage at the US embassy in Iran in 1979, and the Islamic Revolution of that year.
Tents and aid have started arriving
as efforts shift to caring for survivors
Cemeteries in Bam are overflowing with fully clothed corpses, and hundreds of bodies have been tipped into trenches, hollowed out by mechanical diggers.
About 30,000 people were also injured in the quake, which flattened about 70% of the mostly mud-brick buildings in the ancient Silk Road city.
Iranian President Muhammad Khatami said, Iran could not cope on its own, as authorities struggled to accommodate hundreds of thousands of homeless people on a second bitterly cold night.
Tehran's speedy acceptance of help contrasts with its rejection in 1990 of outside doctors, blood supplies, sniffer dogs and used clothes, after an earthquake claimed 36,000 lives and injured 100,000 others.