Colin Barnett has hit out at Wayne Swan's criticism of mining magnates, saying it was the Federal Treasurer's "bungling" not vested interests that caused the demise of the original mining tax.
The broadside came as Prime Minister Julia Gillard backed Mr Swan's essay in The Monthly magazine that claimed Australia's democracy was threatened by mining entrepreneurs opposing good public policy.
Despite admitting that Andrew Forrest and Gina Rinehart constantly pestered him and his office over their projects, the Premier said the mining heavyweights had "no influence over the WA Government".
In an interview on 6PR radio, Mr Barnett said the resources super profits tax, precursor to the minerals resource rent tax, "fell apart" at the meeting when then prime minister Kevin Rudd announced it to premiers.
"There was a bit of a stunned silence and I said WA would not support that, we would never support that and Mr Rudd's jaw just about hit the table," Mr Barnett said.
"He looked across in absolute dismay and said, 'I thought you had agreed to it'. And I said, 'No prime minister, I haven't and I never would'."
Mr Barnett said it appeared it had been Mr Swan's job to negotiate with the premiers but it never happened.
"Wayne Swan bungled that proposal," Mr Barnett said. "It was a bad proposal but he made it worse by bungling it."
A spokesman for Mr Swan said Mr Barnett, as opponent of the RSPT and MRRT, needed to explain why he would "rather give a tax break to a few dozen massively profitable mining companies" than a fair return to citizens for the resources they own.
Ms Gillard said people should read Mr Swan's entire essay, in which he observed that 99 per cent of Australian businesses were motivated by the national interest.
"On the article overall, I think it is important for us as a nation to recognise that public policy has to be at the forefront of interventions in national debates," she said.
Shadow assistant treasurer Matthias Cormann accused Mr Swan of "running a jihad against successful mining entrepreneurs".
Australian Chamber of Commerce and Industry chief executive Peter Anderson said Mr Swan's article and subsequent comments had been unhelpful.