An oil refinery in Abadan, south-west Iran, has been shaken by an explosion.
The blast was caused by the “bursting of one of the furnaces of the sulphur production unit”, state news agency IRNA said on Friday.
No casualties were reported and the agency said production was continuing as usual.
IRNA described the plant as “the oldest refinery complex and one of the biggest in Iran”. It said it supplied 25 per cent of the country's fuel needs.
Industrial accidents are common in Iran. There were a series of similar incidents last year, including a large fire at an oil refinery in southern Tehran.
Some in the republic blame the incidents on Israel. Others consider US sanctions — which almost completely isolate Iran from the rest of the world, complicating the maintenance of industrial facilities — a more likely cause.
A cyber attack last October halted all fuel distribution stations nationwide. Iranian officials accused the US and Israel of being behind the attack.
The city of Abadan in Khuzestan province was also the site of one the deadliest disasters in the country in years.
A 10-storey building that was under construction in the city collapsed on May 23, leading to 43 deaths. It also led to demonstrations across the country, with protesters accusing the authorities of corruption and incompetence.