The world's largest mining company has urged the Australian government to enact a carbon tax before other nations in order to remain competitive.

BHP Billiton chief executive Marius Kloppers yesterday called for a "clear price signal" on carbon dioxide emissions, possibly including both a carbon tax and a limited carbon trading scheme covering power plants.

"We do believe that such a global initiative will eventually come and we do believe that when it does come, Australia will have needed to act ahead of it coming in order to maintain its competitiveness," Kloppers said.

The Anglo-Australian mining giant formerly preferred that Australia act only as part of a binding international climate deal. But Kloppers said BHP Billiton now expects a large number of nations to act separately -- and believes those that act first will benefit when a global climate treaty is ultimately signed.

Kloppers waded into a divisive political debate on Wednesday during a speech in Sydney. BHP Billiton carries political clout in Australia, where minerals are leading exports.

BHP Billiton, which mines nickle, diamonds and other products across Canada, launched last month a $38.5-billion hostile takeover bid for Saskatchewan's Potash Corp. It is the largest pending takeover in the world.

Monte Paulsen reports on carbon shift for The Tyee.