Calgary-based Agrium Inc. isn't giving up on its bid to become the world's No. 2 publicly-traded maker of nitrogen fertilizers.

It announced Thursday it is again extending the deadline in its 10-month-long takeover bid for CF Industries Holdings of Deerfield, Ill.

Agrium CEO Michael Wilson addresses shareholders at the company's annual meeting in Calgary in May 2008. Wilson says CF shareholders clearly like Agrium's offer. (Jeff McIntosh/Canadian Press)

The fertilizer producer and farm supplies retailer will accept shares until Dec.18.

Agrium also said CF shareholders have so far pledged to sell 62 per cent of its stock in response to its offer. Agrium's hostile bid is for $45 US a share plus one Agrium share for a total value of $1.5 billion.

Agrium earlier this month increased its offer by $5 a share, saying that was its "best and final."

"We are pleased that once again, CF stockholders have strongly supported our offer. CF stockholders have sent a clear and unambiguous message to CF's board that they want this deal with Agrium," Agrium CEO Mike Wilson said in a release.

CF, a nitrogen and phosphate producer, has made its own hostile bid for U.S. rival Terra Industries Inc. Shareholders of Terra will vote Friday on whether to elect three directors who have the backing of CF or candidates recommended by Terra's existing board.

CF is incorporated in Delaware, where the law prevents a hostile bidder from buying more than 15 per cent of its shares without the approval of the board.

Agrium threatens legal action

Agrium has said it is considering a lawsuit or trying to elect its own slate to the CF board at its next annual meeting if the board ignores the latest tender results.

Either Agrium or CF stand to become the the second-largest publicly-listed maker of nitrogen fertilizers in the world if one of the bids succeeds.