A roaring blaze has engulfed one of Australia’s two oil refineries, which manufactures about 10 per cent of the nation’s supply and half of Victoria’s.

The out-of-control inferno at the Viva Energy Refinery in Geelong burned all night on Wednesday and into Thursday morning.

The “significant” blaze was reported about 11pm and was still burning early on Thursday morning. In an update on Thursday, Fire Rescue Victoria chief fire officer Michael McGuinness said it would be at least several more hours before it was extinguished.

Witnesses reported hearing loud explosions and the roaring of intense flames when the fire took hold late Wednesday.

Fire Rescue Victoria said firefighters were sent to the ​plant in Corio, less than an hour south-west of Melbourne, after multiple calls from the public.

Residents were warned to shelter indoors, close windows and turn off air-conditioning and heating as thick smoke billowed.

McGuinness said the blaze began in part of the facility where motor gasoline is produced.

“There’s been some sort of leak, there’s hydrocarbons, flammable liquids which very readily caught fire,” he said.

“It was burning in an area of approximately 30 metres by 30 metres. There have been several small explosions.”

FRV specialists were carrying out atmospheric monitoring on Thursday, and Victoria Police, Ambulance Victoria, EPA and Worksafe were at the scene.

Victoria Police said the cause of the fire would be investigated.

There have been no reported injuries and all employees and emergency responders have been accounted for.

Viva Energy has told authorities there is no immediate impact on fuel supplies.

However, Energy Minister Chris Bowen said petrol production had been affected, while jet fuel and diesel production were at reduced levels.

“At this point, the impact is mainly on petrol production, but obviously this is very early days,” Bowen told Nine’s Today program on Thursday. The extent of the damage was not yet clear, he said.

“The fire’s not yet under control, so there’s still some way to go. “This is not a positive development, but obviously there’s a long way to go in terms of working out just what the impact is,” he said.

The oil refinery in Geelong. Photo: Viva Energy

The refinery can process about 120,000 barrels of crude oil a day. It manufactures petrol, diesel, LPG, jet fuel, avgas and low-aromatic Fuel.

According to Viva Energy’s website, the Corio refinery supplies 10 per cent of Australia’s fuel and 50 per cent of Victoria’s fuel. It is the exclusive licensee for Shell fuels in Australia and one of Australia’s largest suppliers of aviation fuel.

The refinery opened in 1954 and is one of only two remaining in Australia.

It’s not yet clear what impact the blaze could have on petrol prices in Australia, which have risen significantly since the war began in the Middle East.

Australia has faced fuel security concerns since Iran all but closed ​the ​Strait of Hormuz after ​being attacked by the US and Israel.

Prime Minister Anthony Albanese said last month the government would halve the excise on fuel and diesel and remove the heavy road user charge for three months to help households cope with a ​surge in costs driven by the Iran war.