CANADIAN fertiliser producer PotashCorp is courting a range of potential “white knight” partners in a determined attempt to see off a $40bn (£25.5bn) hostile bid from mining giant BHP Billiton, the company confirmed yesterday.

The world’s largest potash producer said it had been approached by and had initiated contact with a number of third parties, who it said had expressed an interest in considering “alternative transactions”.

The news came amid suggestions that Brazilian mining giant Vale and Chinese state-owned oil, fertiliser and chemicals group Sinochem have already made preliminary enquiries to PotashCorp over a potential deal.

Speculation over a counter-bid for the firm from China has intensified since BHP launched a formal offer at the end of last week, though the market has questioned the willingness of Canadian authorities to give up such an important strategic asset to an entity controlled by the Chinese state.

But sources close to PotashCorp yesterday insisted that Canada had traditionally proved itself to be one of the most open markets to inward investment, adding that the company would not “close any doors” to willing investors from any country.

Analysts yesterday played down the likelihood of Vale stumping up for a full bid at a higher level than BHP’s $130-a-share offer, though PotashCorp is known to be open to alternative deals such as selling off a minority stake to help it stave off BHP’s approach.

The Canadian firm yesterday laid out its robust defence in a 54-page circular to shareholders against what it called a “highly opportunistic [offer] and an ill-disguised attempt to exploit an anomaly in the equity market valuation of PotashCorp”.

It said that the premium of 16 per cent over the company’s closing stock price on the day before the offer was made does not reflect “the strategic importance, scarcity value or quality of PotashCorp’s assets, nor the unique investment opportunity [the firm] affords to BHP or any other potential acquirer”. The group’s shares have added over a third of their value as investors speculate over the likelihood of an improved offer from either BHP or a rival bidder. Analysts have suggested that BHP can pay anything up to around $170 a share for PotashCorp, depending on the terms on which it can borrow to fund the deal. However, BHP’s own shareholders are likely to bristle at an increased offer, having already suggested that a share buyback would provide better value.