Race to control Australian oil spill

PERTH - The risk of a fire erupting is the biggest danger facing authorities trying to cap an oil and gas rig spill off Australia's northwest coast on Sunday.

At least one ship has been given approval to use a spray to minimise the fire risk while a Hercules aircraft, hired by the Australian Maritime Safety Authority (AMSA), will be allowed to fly near the rig to drop a chemical aimed at cleaning up the spill.

Experts from around the world have been flown in to Perth to devise a plan to cap the 30m wide spill that has grown to at least 12km.

The West Atlas rig, about 250km off the far north Kimberley coast in the Timor Sea, began spewing oil and gas on Friday morning but started showing signs of stabilising on Saturday.

Owned by Norwegian company Seadrill and operated by Thai-based PTTEP Australasia, the rig is now in the middle of a 37km exclusion zone.

The rig was safely evacuated with all 69 workers escaping injury. Another seven initially stayed behind to deal with the emergency.

It's not known what caused the spill, but it's believed to have occurred in wells up to 3,500 metres below the rig, PTTEP chief financial officer Jose Martins said on Saturday.

"Because they are so deep, that's why it's difficult to identify what's going on," he said.

"The leak emanates probably from 2500m below the ocean floor and is coming up through the well platform ... and the West Atlas drilling rig is sitting alongside the platform."

Mr Martins said there was as yet no means of gauging the extent of the environmental damage caused by the spill.

- AAP