France's Credit Agricole last month offered 10.50 euro ($12.57) a share to buy the third-tier Italian lender, for an overall investment of 737 million euros.

The investment fund, which holds 4,72% of Creval, said that the offer by the Italian arm of Credit Agricole "falls short of our view of fair value and fails to reflect an adequate control premium", in a letter sent to Creval's CEO and board, dated Dec. 11 and seen by Reuters.

The investor said that Credit Agricole's approach was "opportunistic" and that considering off-balance tax credits the tangible book value for Creval would be 1.800 billion euros ($2.19 billion), more than one billion euros higher than the current bid.

($1 = 0.8228 euros)

(Reporting by Andrea Mandalà; editing by Giulia Segreti)