The estimated cost of rebuilding after the tremor, in which 31,000 people died and about 30,000 were injured last month, was contained in a document given by UN humanitarian officials to representatives of about 48 countries at a meeting here.

"At present, initial estimates indicate that the long-term recovery could cost anywhere between 700 million dollars to one billion," the document said.

Most of that amount over the next two years is likely to be garnered by the Iranian authorities, but the international community should provide "critical support", the UN document said.

"The reconstruction is, according to the estimates, likely to last about two years and will certainly cost 700 million dollars," said Elizabeth Byrs, spokeswoman for the UN Office for the Coordination of Humanitarian Affairs.

"That's a minimum estimate," she added.

The UN was also giving donors a detailed rundown on its needs over the next 90 days after it appealed for an extra 73 million dollars in aid with the international Red Cross on Thursday.

"This appeal will try to gently bind the first emergency rescue effort with the work and planning needed for reconstruction," Byrs said.

"There will be more appeals in the medium and long-term," she told AFP.

So far about 100 million dollars in aid has been provided by 60 countries since the earthquake struck southeastern Iran on December 26, Byrs said.

About 80 percent houses were destroyed or damaged in Bam and 75,000 people are homeless, the UN estimated.

The new appeal included more than 6,500 tonnes of food for about 100,000 people in the devastated city of Bam.

About 2,500 children orphaned in the earthquake were also receiving help, after about 700 more youngsters who lost their parents were found around Bam over the past week, the UN Children's Fund (UNICEF) said.

Teachers were also being trained to detect children who were deeply traumatised by the quake.

"It's very important, the signs appear three to four weeks afterwards," UNICEF spokesman Damien Personnaz said.

The UN was also on alert following a series of more than 40 tremors and aftershocks in nearby southwestern Iran over the past two days, according to Byrs.

The governor-general of the city of Izeh has asked for 20,000 tents to shelter people sleeping in the open as a precaution.

The area includes three major cities -- Izeh, Masjid, Suleiman -- with populations of 100,000 to 150,000 inhabitants, and authorities fear the smaller tremors might be a sign of a forthcoming major earthquake.

The UN meeting with donors was due to end later on Friday.

TERRA.WIRE