The rig has been leaking oil for 10 weeks
An oil well at the centre of a massive spill in the Timor Sea off the north-west coast of Australia is on fire.
The company which runs the well, PTTEP Australasia, said the fire broke out as it made another attempt to plug a leak deep underwater at the West Atlas rig.
Engineers have been struggling for more than 10 weeks to stop the leak which is spewing out natural gas and oil at an estimated 400 barrels a day.
All workers were reported safe and were being evacuated from the installation.
A director of the company, Jose Martins, said the only way to stop the fire was to plug the leak.
"The measures which we have been able to take so far can only mitigate the fire. They will not stop the fire.
"The best way to stop the fire is to complete the well-kill and stop the flow of gas and oil at the surface from the H-1 well, cutting off the fuel source for the fire."
Australian Resources Minister Martin Ferguson said in a statement that some of the world's leading experts were working to fix the leaking well and respond to this latest problem.
Mr Ferguson said the National Offshore Petroleum Safety Authority had been called out to help fight the fire and that Geoscience Australia and the Australian Maritime Safety Authority were on standby.
But an opposition spokesman, Greg Hunt, accused Environment Minister Peter Garrett of doing nothing to stop the oil leak, which officials say has placed birds and marine species at risk.
"Ten weeks of complacency, 10 weeks of drift, 10 weeks of inaction from Mr Garrett," he said.
"In the absence of action... the prime minister must step in and convene a national environmental emergency task force within the next 24 hours."
PTTEP Australasia said it was planning to use another rig to pump a so-called heavy mud mix into the well later on Monday.