Iranian authorities have announced that a fire affecting the country’s oldest and largest oil refinery in the southwestern city of Abadan has fully been contained, insisting the damage caused by the incident was minimal and had no impact on production.

The public relations office of Abadan Refinery said on Sunday that the fire that had broken out earlier in the day in the canal carrying waste from a crude processing unit was brought under control within only “five minutes”.

It said initially that there was no serious casualties as a result of the fire and that an investigation was going on to determine the exact causes.

However, head of the PR department in the refinery later told the media that a leak from pipes carrying waste from unit 55 of the refinery had caused the fire.

Abadan’s governor Zaynolabedin Mousavi also told the Tasnim news agency that the fire could have been caused by an emergency operation in the refinery to remove incendiaries from beneath the waste pipes.

The official IRNA agency said the fire had no impact at all on production in the refinery which processes around 400,000 barrels of crude each day.

It said firefighters in the refinery acted swiftly to prevent the fire from spreading to other production facilities.

Other reports in the social media, which contained footage showing smoke billowing from the refinery, suggested that damage inflicted on the facility was minimal.

The Abadan Refinery, the biggest in the world until early 1980s, was built in 1912 and at the early stages of oil industry development in Iran.

Iranian authorities have in the past denied terrorism or sabotage as a cause for similar incidents affecting aging oil installations south of Iran.