Two bomb blasts have hit a shopping centre near Iran's border with Iraq, killing four people, state TV reports.
No one has yet claimed responsibility for the blasts
Up to 90 people were injured in the explosions in Ahwaz, capital of Khuzestan province in western Iran.
The attacks, a few minutes apart, took place near an area attacked by several bombs in June.
Ahwaz, which is close to the Iraq border, was the focus of unrest between Arabs and Persians in April, when several people were reportedly killed.
Bombings have been rare in Iran since the war with Iraq ended in 1988.
Saturday's blasts occurred shortly before dusk as shoppers crowded to buy food for the evening meal that breaks the daily fast during the Muslim holy month of Ramadan.
The bombs were planted in rubbish bins, said an interior ministry spokesman.
"They have killed two people and left 41 injured," Jahanbakhsh Khanjani said.
The BBC's Frances Harrison in Tehran said no one has claimed responsibility for the bombs, which were homemade devices.
Ahwaz is the capital of the oil-rich province of Khuzestan, situated close to the border with Iraq and dominated by ethnic Arabs.
Six bombs exploded in June in Ahwaz, killing at least 10 people, days before the presidential election.
A senior official said Americans were behind those attacks and also suggested that Britain might be involved - but he gave no evidence to support his claims.
April's trouble started after a letter circulated on the internet suggested that non-Arabs were being-relocated to the city to dilute its ethnic Arab population.