Giant mining firm BHP Billiton Ltd has announced on Wednesday that it made some revisions on its proposal to acquire Canadian fertiliser maker Potash Corp of Saskatchewan, though the miner admitted that the adjustment were immaterial to the bid's current status.

The company said that changes implemented on the proposal were merely administrative and were made to carry the provisions of specific exemption reliefs granted by the US Securities and Exchange Commission to BHP.

BHP Billiton added that the modifications would also cover "certain other comments to such documents received from the staff of the SEC."

The company also clarified that its standing offer of $US130 per security has remained untouched and the attending terms and conditions related to the takeover bid of Potash Corp were essentially intact.

BHP Billiton had reiterated that its hostile bid to purchase the Canadian firm is still very much active and the company's offer would remain open until October 19, specifically up to midnight of the same day, US time.

Potash Corp, currently the world's largest producer of fertiliser, has already rejected BHP's $US40 billion or $A45.2 billion bid, declaring the initiative as wholly inadequate as it added that the company is now exploring offers from other suitors.

Yet following the formal throwing out of its bid, BHP Billiton had decided to re-channel its proposal to Potash Corp's shareholders, hoping to obtain better response from a crucial segment of the target company.