BHP Billiton is prepared to walk away from its bid for Potash if a rival were to offer a price that exceeds the point where the Anglo-Australian miner sees value for its shareholders, its chief executive said on Tuesday.

"If somebody offers a price at which we cannot demonstrate value for our shareholders, we're probably not going to show, and I think that continues to be the case," CEO Marius Kloppers said in an interview on Canada's Business News Network.

Asked if he'd be prepared to walk away from a bid in that situation, Kloppers said: "Absolutely."