Tens of thousands of Iranians spent a second night in the open after a 7.3-magnitude quake struck near the border with Iraq, killing more than 400 people.
Residents who had fled their homes when Sunday's quake rocked the mountainous region spanning Iran's western province of Kermanshah and neighbouring Iraqi Kurdistan braved chilly temperatures as authorities struggled to get aid into the quake zone.
Iran has declared Tuesday a national day of mourning as officials outlined the most pressing priorities and described the levels of destruction in some parts as "total".
President Hassan Rouhani visited the city of Kermanshah on Tuesday and promised that the government would move swiftly to help those left homeless by the disaster.
"I want to assure those who are suffering that the government has begun to act with all means at its disposal and is scrambling to resolve this problem as quickly as possible," he said.
Rouhani said that all aid would be channelled through the Housing Foundation, one of the charitable trusts set up after the Islamic revolution of 1979 that are major players in the Iranian economy.
The head of the elite Revolutionary Guards, Major General Mohammad Ali Jafari, said the immediate need was for tents, water and food.