(Reuters) - Foster's Group Ltd., Australia's largest brewer, said it had rejected an offer worth up to $2.5 billion for its wine business from a private equity firm and would continue to pursue the demerger of its wine unit. The deal would have been the largest buyout by a private equity firm in the Australian market since 2007. International private equity firms have shown renewed interest in cheap Australian assets this year, snapping up hospital owner Healthscope in July for A$1.99 billion.