A blaze at an oil rig off Australia was brought under control on Tuesday when experts managed to plug a leak that has spewed tonnes of crude over the past 10 weeks, the well's operator said.

PTTEP Australasia said its fifth attempt to plug the leak had been successful and it had stopped the main fire at the wellhead platform.

"The fire at the West Atlas rig at Montara wellhead platform has been put out after heavy mud had been successfully injected into the leaking well," the company said in a statement.

"Some material on the topside of the West Atlas rig might still be on fire but it is expected to be extinguished as the fuel source burns out," the Australian Associated Press quoted PTTEP as saying in a separate statement.

The company said the situation appeared to be stable and the well pressure was being maintained.

The rig, some 250 kilometres (155 miles) off the coast, caught fire Sunday during an attempt to stop the leak, which has dumped thousands of barrels of oil into the Timor Sea since it began gushing into the water on August 21.

The government has ordered an inquiry into the emergency while environmentalists have expressed concerns about the pristine waters off the northwest coast, which are home to whales and dolphins.

Resources and Energy Minister Martin Ferguson earlier said the accident, the first on such a scale in 25 years of offshore drilling, had "clearly had an impact on the standing of the oil and gas industry in Australia".

"We are relieved and thankful that we have killed the well and stopped the main fire," said PTTEP Australasia director and chief financial officer Jose Martins.

"We still have a lot more work to do and our priority is now to determine the best method of plugging the H1 well bore."

An Indonesian non-governmental organisation earlier said the spill had ruined about 80 percent of the catch for some fishermen, while conservation group WWF said it was one of Australia's biggest environmental disasters.

"We do not underestimate the significantly increased technical complexity, logistical challenges and hazards of the work now required in the wake of the damage caused by the fire to the wellhead platform and the West Atlas rig," Martins said.

"We will continue to work closely with AMSA (Australian Maritime Safety Authority) to assist in the oil spill clean-up operations and with (Australia's government) in continuing to roll out what is likely to be the largest industry environmental monitoring programme ever seen in Australia."