At the scene of the disaster however residents, desperately searching for bodies and possible survivors with simple tools, bewailed what seemed to them to be the sluggishness of the response.
Small teams from the Iranian Red Crescent did what they could, but to those who escaped the delay in bringing in sniffer dogs and heavy equipment seemed painfully slow.
"We are offering humanitarian assistance," US President George Bush's spokesman said on Friday. "This is a terrible tragedy."
The offer of aid comes despite the absence of diplomatic relations between the US and Iran for the last 25 years.
Turkey, which has plenty of experience in earthquake relief work, sent a plane carrying search and rescue teams and humanitarian aid to Iran. The aid included tents, blankets and medicines.
Jordan said it was preparing a plane loaded with aid for Iran. The Jordan Hashemite Charity Organisation said the aid would include tents, medical equipment and food.
Medicines will be rushed in first
UN officials said they were releasing an immediate emergency grant of $90,000 to help Iran handle the aftermath of the quake and had sent experts to help assess the damage.
The world body's Office for the Coordination of Humanitarian Affairs (OCHA) said the UN team, due to reach the ancient Silk Road city of Bam in southeastern Iran later in the day, would also work to mobilise and oversee international assistance.
The immediate need was for medicines, tents, mobile hospitals, electricity generators, water purification equipment and blankets, OCHA's Madeleine Moulin-Azevedo said.
The Tehran authorities had not yet identified any urgent requirement for food supplies, OCHA said.
The UN children's fund UNICEF said it was sending first aid kits and medical supplies. It called for $350,000 in donations.
Russia's Emergencies Ministry, highly skilled in reacting to frequent natural and man-made disasters, has offered rapid-response units of doctors, paramedics and sniffer dog handlers to help find people buried under rubble.
Itar-Tass news agency quoted the Emergencies Ministry as saying planes would leave for Iran early on Saturday with 100 experts for searching collapsed buildings, 10 doctors and search dogs. Russia has close ties with Iran.
France was sending a field hospital and the Czech Republic had also offered aid.
The European Union Commission in Brussels said it would provide some 800,000 euros in humanitarian aid from the funds of Echo, its humanitarian office.
Italy, as current president of the European Union, will coordinate EU aid to avoid duplication.
"This is the first time EU coordination is taking place for a disaster,"
Agostino Miozzo, EU
"This is the first time EU coordination is taking place for a disaster," said Agostino Miozzo who is coordinating the EU aid. "It's important not to duplicate efforts, for example, to make sure that several countries don't send field hospitals to the exact same place."
In Berlin, German Foreign Minister Joschka Fischer offered Tehran help in rescuing earthquake survivors who may be trapped in collapsed buildings and to repair damage.
The International Red Cross is preparing an appeal for $8 million to help the victims.
The appeal will cover emergency supplies such as tents, blankets, and possibly field hospitals, said Roy Probert of the International Federation of Red Cross and Red Crescent Societies.