The chief executive of Scottish-based Capricorn Energy stressed this morning that the planned tie-up with Tullow Oil can deliver “significant” long-term value for shareholders.
But Simon Thomson also revealed that the company was exploring possible alternative transactions.
His comments came as Capricorn announced its latest half-year results, and they follow on from opposition by some of the firm's shareholders to the deal.
The CEO said: "The board continues to believe that the proposed merger with Tullow can deliver significant long-term value for shareholders through creating a leading, Africa-focused energy company."
However, he added: "The board is also mindful of the impact of external factors and market conditions and is, as always, assessing all options to maximise value for shareholders.
"The company is exploring a number of expressions of interest relating to alternative transactions, and is engaging with those parties expressing interest to evaluate potential outcomes."
It was at the start of June when the all-share merger deal with Tullow was announced, valuing the combined business at roughly £1.6billion.
Tie-up in peril
However, Bloomberg reported last month that the tie-up appeared to be in peril, with more than a quarter of the Capricorn shareholder base saying they planned to vote against the transaction.
Investors Madison Avenue Partners, Kite Lake Capital Management, Legal & General Investment Management, Newtyn Management and Palliser Capital UK all said they opposed the deal. They represent more than 27% of Capricorn's shareholder base, according to regulatory filings.
Bloomberg says the takeover requires the support of at least 75% of Capricorn's shareholders who cast ballots.
The investors said they saw little merit to the deal and few synergies between the companies.
"The transaction undervalues Capricorn, benefits Tullow at our expense, and trades the certainty of our cash for speculative Tullow stock," said Eli Samaha, managing partner at Madison Avenue Partners.
Capricorn (formerly known as Cairn Energy) is one of Scotland's most successful home-grown oil-exploration companies, with its HQ in Edinburgh
Cairn was founded in 1981 by ex-rugby international Sir Bill Gammell.
Large Indian find
It was successful in finding a large oil field in India, but not with controversial drilling near Greenland. It has since withdrawn from both countries.
The merger with Tullow would see the joint company, listed on the London Stock Exchange, focus on its current assets in Africa and new opportunities for drilling on the continent.
Tullow has operations in Gabon, Ivory Coast and Kenya.
Capricorn was successful drilling for gas in Senegal and sold its stake there, with its focus now on Mauritania and onshore in Egypt.
Its portfolio also includes prospects in the UK North Sea, Israel and Mexico.
The combined firm would have production of an estimated 100,000 barrels of oil per day, and identified reserves of 343million barrels, mostly oil.