BHP Billiton has taken the axe to more than $US30 billion in spending on Australian expansion projects, in the clearest sign yet that the nation is past the peak of its resources boom.

BHP’s decision to change its strategy on its Olympic Dam expansion came as the company announced a 35 per cent slide in net profit

A plan of the proposed expansion at Olympic Dam from the draft Environmental Impact Statement 2009.

"It doesn't really make a lot of sense in this market for them to be engaging in a major capital spending program and to be bringing more supply onto the market in a time when prices are softening," said Gavin Wendt, publisher of resources newsletter Mine Life.

"The deposit isn't going anywhere and this decision gives them the sort of flexibility down the track to expand," he said. "In this environment it makes sense to maintain the status quo."