Foster's Group (FBRWY), Australia's largest brewery known for its Foster's lager, said Wednesday that it has received and rejected an unsolicited expression of interest from an international private equity firm to acquire its wine assets, Treasury Wine Estates.

The Melbourne-based company didn't identify the private equity firm that expressed interest, but it did disclose the proposal involved a cash consideration of between A$2.3 billion and A$2.7 billion ($2.1 billion to $2.5 billion) for 100% of the assets. Revenue for the wine business for 2010 was A$1.9 billion. Foster's wine business is the world's second largest after Constellation Brands (STZ).

The company said in a statement the proposed value range "significantly undervalues Treasury Wine Estates and its future prospects." Foster's added that the proposal had a "high level of conditionality," a "requirement for exclusivity" and other terms that "reduce its value and certainty." The board "continues to consider that a separation of the Wine business from the Beer business through a demerger is most likely to represent the best outcome for all Foster's shareholders."

Foster's said in May it was splitting its wine and beer businesses. It has since been the subject of acquisition reports. About two weeks ago, it was reported that London-based SABMiller (SBMRY) was mulling a £7 billion, or $10.9 billion, bid for the beer-making part of Foster's, Carlton & United Breweries. Japan's Asahi Breweries (ASBRY) might also be interested, other media reports claimed. And previous reports linked Foster's to potential offers from China's Bright Food Group and Tsingtao Brewery and to Canadian brewer Molson Coors (TAP).

Analysts now say that the recent development puts the whole company in play as potential buyers know they can unload the less profitable wine-making business and keep the more lucrative beer business, "which is seen as a cash cow with some of the highest profit margins in the brewing world," according to Reuters.

Shares of Foster's closed 4.5% higher at A$6.34 in Sydney as investors hoped the news would fuel other bids.