At least eight people were killed and 46 injured in two blasts in the south-western Iranian city of Ahwaz, police said.
No one has yet claimed responsibility for the blasts
The two bombs exploded outside a privately-run bank and a government office in the city in Khuzestan province, which borders Iraq.
Iranian President Mahmoud Ahmadinejad had been due to give a speech at a religious centre nearby.
But his office told the BBC the visit had been cancelled due to bad weather.
Mr Ahmadinejad's media chief said the president had feared the weather would have prevented people from attending his meetings in the city.
He did not believe the bombs were linked to the planned visit, because there had been a series of similar blasts last year.
A spokesman for the Police Task Force said one bomb had exploded on Kianpars Street, inside the Saman Bank, and had killed at least six people and wounded 15 others.
The spokesman said the second explosion took place on Golestan Road next to the Natural Resources Department, a state environmental agency, causing injuries but no deaths.
Initial investigations found the devices had been percussion bombs, which produce a loud bang but usually do not cause damage, he added.
Nobody has claimed responsibility for the blasts, but one Iranian MP said he thought separatists were behind the attacks.
"The blasts in Ahwaz are always perpetrated by counter-revolutionary elements, those who engage in activities against Iran from beyond our borders and Britain," Nezam Molla-Hoveyzeh told reporters.
"A satellite network has been provoking ethnic and nationalistic issues recently; and some networks outside the country have been active to encourage separatism in Khuzestan."
The oil-rich province, which is home to about two million ethnic Arabs, was rocked by a wave of unrest last year, including bomb blasts in June and October.
The government blamed the attacks on the UK, whose forces are just across the border in southern Iraq, but British officials denied involvement.
In November, protests erupted in Ahwaz after ethnic Arabs accused authorities of discrimination.