Spill inquiry welcomed but criticised

An inquiry into a 10-week oil spill off Western Australia has been welcomed by all quarters but the Greens and the federal opposition have been critical of some elements of the probe.

Oil began leaking from PTTEP Australasia's Montara well head platform in the Timor Sea, more than 200km northwest of WA's Kimberley coastline, on August 21.

The Thai-based company engaged a team of experts to pump heavy mud into the leaking well but it took more than 10 weeks before it was finally plugged on Tuesday.

On Sunday a fire broke out at the platform as specialists attempted to plug the well.

Resources Minister Martin Ferguson announced an inquiry into the incident and the response to it, on Thursday.

Former senior public servant David Borthwick will head up the inquiry, which will be able to summon witnesses, take evidence on oath and require individuals and corporations to hand over relevant documents.

"The powers I've been given, as I understand it, do enable me to bring forward evidence that might otherwise be reluctantly given," Mr Borthwick told reporters in Canberra.

Mr Ferguson insisted the inquiry would be held at arms length from government.

The appointment of Mr Borthwick, a recently retired secretary of the Department of Environment, Water, Heritage and the Arts, was not ideal, Greens Senator Rachel Siewert said.

Senator Siewert said the inquiry was welcome but she was concerned about Mr Borthwick's credentials.

"I am concerned, while I have no problems with Mr Borthwick as a bureaucrat or as a person, I am concerned they have appointed someone who is an ex-bureaucrat, who has worked for government," Senator Siewert told reporters in Perth.

"But most importantly he doesn't have judicial or investigative experience."

Senator Siewert said the government needed to clarify if the inquiry would conduct public hearings.

"While the terms of reference appear to be comprehensive we need the government to clarify that the commissioner will be able to review the government's involvement in this whole process and their decision making process and actions," she said.

"Very concerning about the inquiry however, is that they haven't clarified that the inquiry would definitely be a public inquiry.

"The way we read the terms of reference and also comments that Mr Ferguson and Mr Borthwick made don't give us confidence it will be a public inquiry."

Federal Environment Minister Peter Garrett said it would be up to Mr Borthwick as to whether public hearings were held.

"My expectation would be that he would give pretty open thought to the opportunity for public inquiry participation but it's a matter for the commissioner," Mr Garrett told reporters in Perth.

Both the Greens and the opposition have called for the government's role to be scrutinised.

Opposition environment spokesman Greg Hunt said he wanted to know what, if anything, Mr Garrett had done throughout the spill.

"Given that the company has warned that it could take seven years to clean up the environmental damage, Peter Garrett must start to become engaged in this matter," Mr Hunt said.

Mr Garrett defended his response to the spill.

"I would say that I responded immediately, quickly and thoroughly in relation to this incident, as was the response of relevant authorities and the government ...

"I went to the site, I instituted an environmental monitoring plan immediately, we took expert advice on the best way to approach that task ...

"We had experts in the field and we had observation surveillance under way, always recognised that this accident was a critical one and it was important to have a good and clear understanding as soon as we possibly could on what the environmental impacts were."

PTTEP said on Thursday it would co-operate fully with the inquiry.

"The company welcomes the opportunity for all the facts to be placed on the public record and fully assessed," it said in a statement.

PTTEP chief financial officer Jose Martins revealed on Tuesday the company believed it knew the cause of the leak but said he did not want to speculate ahead of the inquiry.

Late on Thursday engineering and construction company Clough Limited announced PTTEP had terminated its contract to complete offshore facilities at its Montara oil field.