UPDATE 1-CF extends Terra financing to Dec. 31

* CF extends financing to end December

* CF says cannot extend again unless signs deal

NEW YORK Dec 1 (Reuters) - CF Industries (CF.N) said on Tuesday it had exercised its right to extend the $2.5 billion financing commitments for its hostile takeover bid for rival Terra Industries Inc TRA.N to Dec. 31.

Last month, shareholders of Terra elected three new board members backed by CF, but Terra's management has so far rejected CF's offers.

CF said it does not have the right to extend the financing commitments beyond Dec. 31 unless a merger agreement is signed by the date.

CF is itself the target of a hostile takeover attempt by Canada's Agrium Inc (AGU.TO).

Shares of CF and Terra were unchanged in premarket trade.

(Reporting by Matt Daily, editing by Dave Zimmerman)