DOW JONES NEWSWIRES 
 

Agrium Inc. (AGU) again extended its offer to acquire rival CF Industries Holdings Inc. (CF) despite only a small increase in shareholder support, prolonging a three-way turf battle in the fertilizer sector.

Agrium is extending its offer, worth $4.4 billion, until midnight Sept. 22.

As of Friday, about 10.5 million CF shares had been tendered and not withdrawn, about 100,000 more shares than at the end of July. CF Industries shareholders pulled back their tendered shares in droves during July. CF has said it will continue its own takeover effort of fellow fertilizer maker Terra Industries Inc. (TRA), which also has repeatedly rebuffed a potential deal.

Agrium had threatened to walk away from its buyout effort, consisting of $40 in cash plus one Agrium share per CF share, if a sufficient number of CF holders didn't show support, but instead continues to extend its tender offer.

There are about 49 million CF shares outstanding.

Shares of Agrium and CF closed at $48.19 and $82.87, respectively, Friday and didn't trade premarket Monday.

-By Tess Stynes, Dow Jones Newswires; 212-416-2481; tess.stynes@dowjones.com