An oil rig off the coast of Australia, which ruptured two months ago spilling millions of litres of oil into the Timor Sea, burst into flames on the weekend, causing more alarm for environmental campaigners.

The damaged West Atlas rig, situated 125 miles off the coast of West Australia, caught fire on Sunday during the latest attempt to plug the leak which covered an area of at least 5,800 square miles in the ocean.

The Australian Resources and Energy Minister Martin Ferguson said the rig's Thai-based operators PTTEP Australasia would make another attempt to stop the spill by filling the well with heavy mud.

"Therefore removing the source of gas which is fuelling the fire," he said.

The company said the only way to extinguish the blaze which engulfed the deck and well-head platform, was to plug the well casting, which was 25 centimetres in diameter, more than 2 miles under the sea bed.

"The measures which we have been able to take so far can only mitigate the fire, they will not stop the fire," the company's chief financial officer Jose Martins said.

"The best way to stop the fire is to complete the well-kill and stop the flow of oil and gas at the surface of the H1 well, cutting off the fuel source for the fire."

No one was onboard the rig when the fire started and workers on the West Triton relief rig, stationed 1.2 miles (2km) away, were safe from the enormous blaze.

About 400 barrels of oil a day have been leaking from the West Atlas oil well since it ruptured August 21. So far the spill has cost the company $177 million.

Australian Petroleum Production and Exploration Association (APPEA) chief executive Belinda Robinson said the main priority now was to ensure the safety of people involved in sealing the well.

“The safety and emergency planning of the company, the international experts and the responsible government agencies have ensured that no personnel were injured when the fire on West Atlas began yesterday,” Ms Robinson said.

“Right now the focus is on successfully stopping the well leak safely and minimising any environmental impact.”

Last week scientists surveying the effects of the oil spill said it would have a detrimental effect on the environment and the local marine life, and compared its long-term effects to those of the Exxon Valdez spill near Alaska in 1989.

Conservationists estimated that the oil covered an area of at least 5,800 square miles and described the incident as an “environmental disaster”.

Gilly Llewellyn, a WWF team member who surveyed the spill, told The Times last week : “We were in an area that is teeming with marine life and we literally found ourselves in a sea of oil that reached as far as we could see. It was sickening, because we were seeing dolphins surfacing in the oil and birds feeding in it.”

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