Dairy product manufacturer Warrnambool Cheese and Butter Factory Company (ASX:WCB) has recommended shareholders reject a recent confidential takeover proposal.

The unsolicited proposal is incomplete, non-binding and subject to multiple conditions, the company announced in a statement, urging shareholders not to sell.

The offer also undervalues Warnnambool, which has improved its prospects significantly in the past six months, the statement added.

WCB shares have risen 17.3% to $2.58 today, after an 8.4% spike yesterday.