Agrium Inc. (AGU) said it sweetened its hostile offer for rival fertilizer maker CF Industries Inc. (CF) to around $4.1 billion Monday, though it target's share price continued to lag the revised terms.

The Canadian predator also extended the expiration of its bid by almost a month until June 15, after the scheduled close of CF's own unsolicited bid for smaller U.S. rival Terra Industries Inc. (TRA).

Agrium's CEO, Mike Wilson, and the company's advisors have sought talks with CF, according to people close to the situation, though no meetings are planned.

The three-way tussle, now in its fourth month, has seen CF reject Agrium's approaches, and cast them as an effort to disrupt its own pursuit of Terra and prevent consolidation in the wholesale fertilizer sector.

Agrium, a leading retail distributor, boosted the cash component of its offer to $40 a share from $35, plus one of its own shares for each CF share, valuing the package at $85.20 based on May 8 closing prices.

CF shares continue to trail the offer, recently trading up 1.4% at $74.86. Agrium shares were down 1.6% at $44.49.

While Agrium touted a 53% premium to its own pre-bid level in February, the broader fertilizer sector has strengthened in recent weeks after a prolonged period of weak demand and high raw material costs.

CF acknowledged receipt of the bid and said its board "will evaluate the revised proposal carefully."

Terra, the smallest of the trio, has rejected CF's approaches and also pushed back the date of a shareholder vote from May until at least June 8.

The two sides had not engaged in any discussions prior to CF's annual meeting last month, where Agrium had urged CF shareholders to withhold their votes from the board's slate. Both sides claimed victory, with the three directors re-elected by more than 75% of shareholders, while Agrium had sought to dissuade at least 20% from backing the slate.

Meanwhile, CF has made its own bid for a third peer, Terra Industries Inc. (TRA). CF has continued to call Agrium's offer "grossly inadequate."

The jockeying for position comes as fertilizer producers look to take advantage of the drop in sector stock prices since last summer to buy up production capacity ahead of an expected rebound in prices.

Agrium said as of midnight May 8, 1.3 million of CF's 49.1 million shares outstanding had been tendered.

-By Doug Cameron, Dow Jones Newswires; 312-750-4135; doug.cameron@dowjones.com

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