The WA Treasurer Troy Buswell has raised the prospect of selling assets within ports as the government tries to claw back Western Australia's AAA credit rating.

Global ratings agency Standard and Poor's yesterday lowered the state's long-term investment ranking to AA+, prompting the government to float potential asset sales as a way to combat climbing debt levels.

Mr Buswell has ruled out halting the Elizabeth Quay or Perth Stadium projects but has told the ABC the government is considering selling port owned assets.

"There's certainly assets that port authorities hold with individual berths, individual loading facilities, and the like, that don't need to be held by the port authorities, so you'll have private investment within the envelope of the state-controlled port authority," he said.