Nov. 1 (Bloomberg) -- PTT Exploration & Production Pcl said a fire broke out on a drilling rig in the Timor Sea off northwestern Australia during efforts to plug the well that has been leaking oil for 10 weeks.

PTTEP was pumping heavy mud from its West Triton rig into the leaking Montara well via a separate shaft when the blaze started at the West Atlas drilling rig and well-head platform, the Bangkok-based company said today in an e-mailed statement.

“All personnel on the West Triton and on nearby work vessels are reported to be safe,” PTTEP said in today’s statement. “Non-essential personnel are being evacuated” from the facility.

Oil, gas and condensate began seeping from the well 2,600 meters (1.6 miles) below the seabed into the Timor Sea off the west Australian coast on Aug. 21. Costs have reached A$177 million ($162 million) as more than 300 people are working to deal with the spill, which may have spewed more than 28,000 barrels of oil into areas inhabited by dolphins, sea turtles, and humpback whales. This weekend marks the fourth attempt to plug the leak.

“The government remains deeply concerned about this incident,” Resources and Energy Minister Martin Ferguson said in an e-mailed statement today. He also called on state and federal bodies, including the National Offshore Petroleum Safety Authority, to assist the company as it responds to the fire.

‘Well Kill’

The leaking well was intercepted at 9:30 a.m. Darwin time today and “operations commenced to complete the ‘well kill’ by pumping heavy mud into the leaking well from the West Triton,” the company said. “While operations were continuing, a fire broke out.”

Efforts to cap the oil leak have been complicated by the challenge of intercepting a 25-centimeter diameter steel well casing so deep below the seabed.

PTTEP, Thailand’s only publicly traded oil explorer, has estimated the well has been spilling 300 to 400 barrels of oil a day into the Timor Sea, making it the third-biggest spill in Australia’s history, according to figures from the Maritime Safety Authority.

The Montara well is in water 80 meters deep and some 690 kilometers (430 miles) from Darwin in the Northern Territory and 250 kilometers from Truscott on Australia’s northwestern Kimberley Coast.

To contact the reporter for this story: Jacob Greber in Sydney at jgreber@bloomberg.net

Last Updated: November 1, 2009 01:53 EDT