On Nov. 14, Australian oil and gas company Central Petroleum rebuffed a takeover offer from its main lender, Macquarie Group, that valued the company at AU$76 million (US$57 million), but left the door open to a higher offer.

Shares in Central rocketed as much as 485% to twenty Australian cents, well above the AU$0.175 per share that Macquarie offered, after Central said it would open its books for Macquarie to review in the hope the bank would return with a better bid.

"The board of directors of the company has determined that the proposal is not in the best interests of shareholders," Central said in a statement to the Australian Stock Exchange.

Central said it would give the bank, which already owns 2.3% of its shares, access to its books "to provide Macquarie every opportunity to reconsider its proposal."

Macquarie was not immediately available for comment.

Central Petroleum produces gas from conventional fields onshore in the Northern Territory, and sees itself as well-positioned to meet a shortfall of gas in the eastern Australian market, or to supply LNG to plants that chill the gas for exports.

.(US$1 = AU$1.3284)