Iran's President Hassan Rouhani has vowed to "find the culprits" responsible for buildings collapsing in a 7.3-magnitude earthquake on Sunday.

He suggested that government-built buildings had collapsed while privately-built ones remained standing.

As he spoke in the worst-affected city, Sarpol-e Zahab, he gestured to two buildings, one of which had collapsed while the other had not.

More than 400 people were killed and close to 8,000 injured in the quake.

Although an earlier report from the state news agency Irna said 530 people had died, the death toll was later revised downward, to 432.

The government is scrambling to get aid to Kermanshah province in the west of the country, where hundreds of homes were destroyed and people have spent two nights outdoors in the cold.