Mr Browning said AlintaGas was just weeks away from board approval for the first of its $100 million plus co-generation plants at Alcoa's Pinjarra alumina refinery, south of Perth.

"We cant imagine how anyone else is going to be able to put a unit up and compete with the kind of pricing we've got with this co-generation unit," Mr Browning said.

"And I think that if the government proceeds with that power procurement process, they're going to lock Western Power into contracts that are going to be out of the money.

"There's the potential for stranded capacity and so on."

Western Power is scheduled to call for private sector expressions of interest this month to build the new $450 million, 300 megawatt base load power station.

In response to Mr Browning comments, Western Power's head of generation, Mark Chatfield would not concede that the Alcoa-AlintaGas co-generation deal would produce cheaper electricity than the power procurement process. "It would be anti-competitive for us to simply abandon the process," he said.

Mr Chatfield added there were question marks about whether the Alcoa-AlintaGas deal would ever go-ahead.