An alliance of domestic gas producers has strongly criticised the decision to allow the proponents of the Gorgon gas project to market the commodity jointly .

The Australian Competition and Consumer Commission yesterday approved the joint selling arrangements proposed by Chevron, Shell and Exxon-Mobil.

The Gorgon project on Barrow Island is expected to produce about 15-million tonnes of natural gas a year at peak production.

Tony Peterson from the DomGas Alliance says the ACCC's decision will ultimately drive up the price of gas for consumers.

"We don't believe that the ACCC approach, that less competition is OK is warranted at all," he said.

"We think there should be more competition in the market here in WA, and that means that every company selling gas should be doing so independently."