Oil and gas group Ophir Energy has confirmed details of its possible takeover offer for UK-listed peer Salamander Energy, valuing the company at around £300m.In a joint announcement, the parties announced the proposed terms of the share-exchange deal, which comes at a 44.5% premium to Salamander's share price prior to its initial statement in October confirming the talks.Based on Ophir's share price of 202.7p on 24 October, the offer of 0.5719 Ophir shares for each Salamander share represents a value for the latter of 115.9p per share.The boards of both companies "believe that there would be compelling strategic logic for a combination of the two businesses that would substantially benefit the shareholders of both companies"."The combined business would have a strong balance sheet, enhanced operating capability across the core operating geographies of Africa and South East Asia, and deep expertise across key technical and commercial functions," they said.Salamander's board said it expects to recommend the proposed offer.The group had also been in talks with another consortium of investors, CEPSA and Strategic Energy, but those discussions are no longer ongoing.