An explosion rocked Iran’s and Middle East’s oldest oil refinery in southwestern city of Abadan in the oil-rich Khuzestan province overnight, state media reported on Friday.

According to the government’s official news website, IRNA, the blast was caused by the bursting of one of the furnaces of the sulphur production unit of phase three of Abadan Oil Refinery during the start-up operation, causing a huge explosion.

The blast apparently had no casualties, and IRNA claims that production at the refinery continues as usual.

This is the second incident at the Abadan refinery, which supplies around 25 percent of the country’s fuel needs, this year. In April, a section of the refinery caught fire but the blaze was contained with no fatalities or injuries. 

Abadan, near the Persian Gulf coast, is Iran’s largest refinery with a daily capacity of 430,000 barrels of crude, producing liquefied petroleum gas, gasoline, kerosene, gas oil, jet fuel, furnace oil, bitumen, petroleum solvents, sulfur, and naphtha. Abadan refinery, opened in 1912 by the Anglo-Persian Oil Company originally as a pipeline terminus, quickly became one of the world's largest refineries and was an important supplier to the British military.

Several explosions and fires in Iranian military and industrial sites − including pipelines and refineries − since mid-2020 have not been fully explained by authorities. However, they have blamed Israel for a series of spectacular sabotage attacks on nuclear facilities, including two explosions at Natanz uranium enrichment center. Israel has not taken responsibility for any incident.