Speaking at a press conference, Martins also said that yesterday's attempt to kill the H1 well may have triggered the blaze.

"It is very hard to be certain, but it may be that operations yesterday could have started the fire," he said.

"The measures which we have been able to take so far can only mitigate the fire, they will not stop it. The best and safest way to stop the fire is to kill the well by pumping heavy mud into the leaking well.

“The mixture of heavy mud is designed to stopping the flow of gas and oil at the surface of the H1 well, cutting off the fuel source. This should kill the well and stop the fire.”

He admitted the procedure may not succeed at first attempt.

"If we don't do it the first time we can still have another go ... [we will] rework the density of the mud," he said.

Martins said the West Atlas' cantilever deck had collapsed onto the wellhead platform, but an assessment of the structural integrity of both the platform and jack-up would not be possible until the fire is extinguished.

However, he said there was "a large risk [of collapse] at the West Atlas".

Seadrill spokeswoman Hilde Waalen said the West Atlas, which is fully insured for $200 million, may be a “total wreck”, but added an accurate assessment of the damage can only be made once the wellhead fire is doused.

According to Seadrill's fleet status report, the Singapore-built KFels B-class design jack-up, which was delivered in the third quarter of 2007, has been operating on a dayrate of $255,000 since October.

Earlier, PTTEP said well control experts are mixing about 4000 barrels of a heavy density mud to pour down the relief well. An attempt to kill the well and extinguish the fire will be made after first light tomorrow.

In the meantime, sea water is still being pumped into the blownout H1 bore via the relief well.

PTTEP said eyewitness reports indicate there is little or no oil being released into the ocean from the wellhead platform, indicating the oil and gas being released from the bore is burning off.

The company declined to give a revised estimate for the cost of the incident, although sources believe the figure is likely to top A$180 million (US$161.8 million). The Thai operator has submitted an insurance claim to help it meet costs.

Meanwhile, Australia's Prime Minister Kevin Rudd told Fairfax Radio he was disturbed by the incident.

"Do I think this is acceptable? No, I don't. Are we angry with this company? Yes, we are. Are we trying to do everything we can to get this under control? You betcha," he said.

Federal Energy Minister Martin Ferguson has pledged a full investigation into the accident, a move backed by the upstream sector's peak body, the Australian Petroleum Production & Exploration Association.

However, Western Australian Premier Colin Barnett - who supported calls for a wide-ranging investigation - claimed blowout and fire was a "very serious failing in the petroleum industry".

Barnett added PTTEP should be "up front" about the volumes of oil, gas and condensate spilling into the Timor Sea.

He told the Australian Associated Press: "I think there are some doubts arising about the incident and how it occurred. We do have some concerns about the management of the incident."

The blaze erupted yesterday as the West Atlas' sister rig, the West Triton, which is about two kilometres from the platform, managed to intercept the blownout H1 wellbore on its fourth attempt.

The H1 well blew out on 21 August.

An estimated 500,000 litres of oil and condensate has spewed into the Timor Sea since the blowout.

PTTEP said 300 to 400 barrels of oil per day was leaking from the damaged wellbore, but the Department of Resources, Energy & Tourism told a Senate committee last week it believed up to 2000 bpd is being leaked into the sea.

The Associated Press has uploaded video footage of the blaze here. The film includes some audio from an interview with Greens leader Bob Brown.

Published: 02 November 2009 09:27 GMT  | Last updated: 03 November 2009 06:45 GMT