The Chamber of Commerce and Industry has welcomed a Labor promise of a $400 million payment to Western Australia to make up for the state's GST revenue shortfall, but said "short-term top-ups will no longer cut it".

Federal Opposition Leader Bill Shorten announced the plan to lift WA's GST share to a 70 cent in the dollar in Perth on Wednesday without changing the current formula for distributing revenue from the tax to the states.

Leader of the Opposition Bill Shorten at a press conference at the North Metropolitan Tafe in Northbridge after announcing the $400 million GST top-up on Wednesday. Credit:AAP Image/Richard Wainwright

"We will help Western Australia without hurting the eastern states - with more money and more certainty for the future," he said in a joint statement with shadow treasurer Chris Bowen.

But CCI chief economist Rick Newnham said Western Australians were "looking for a long-term solution which is in the national interest".