London-listed Ophir Energy Plc said March 21 it agreed to be bought by Indonesian oil and gas group Medco Energi Internasional Tbk for a sweetened cash bid of 408.4 million pounds (US$539 million) after previously agreeing to a lower offer.

Under the terms, Ophir shareholders will receive 57.5 pence per share in cash, the companies said in a joint statement. That is up from the previously agreed 55 pence per share.

The increased offer comes after the Financial Times reported that hedge fund Petrus Advisers, which owns 3.94% of Ophir, planned to vote against Medco's bid because it undervalued the company.

Petrus in February had called for alternatives to Medco's buyout offer and asked the company to put Petrus-backed directors in charge of overseeing the proposed changes.

Ophir, which explores and produces oil and gas in Asia and Africa, and Medco were not immediately available to comment on the Financial Times report.

Ophir also received an offer earlier this month from Coro Energy Plc, according to which Ophir shareholders would receive 40 pence in cash, and in addition, shares in Coro for each Ophir Share, resulting in an ownership by Ophir shareholders of between 85% and 95% of the enlarged company.

Ophir said March 21 that Coro does not intend to proceed with its proposal after the deal between Ophir and Medco.

Medco said its offer of 57.5 pence per share is final and would not be increased. Ophir's directors recommended that the shareholders vote in favor of the deal, it said.

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A meeting in connection with the increased offer will be held on March 25, Ophir added.

The offer price is at a premium of about 73% to Ophir's closing price on Dec. 28, the last trading day before Medco first announced a possible offer and a premium of about 2.7% to Ophir's March 20 close of 56 pence.

Medco plans to fund the deal by proceeds of a credit agreement and from its existing cash resources.

The Jakarta-headquartered company had previously said that the deal would be immediately accretive in the first full year to its EBITDA and net income.

Ophir in January rejected a $437 million, or 48.5 pence per share offer from Medco, saying it undervalued the company.

Standard Chartered Bank acted as financial adviser to Medco while Morgan Stanley and Lambert Energy Advisory advised Ophir.

Founded by oil and gas tycoon Arifin Panigoro, Medco has made sizeable acquisitions in recent years, including leading a $2.6 billion acquisition of the Indonesian unit of Newmont Mining Corp. in November 2016. (US$1 = 0.7583 pound)