Thailand’s state-owned energy firm PTT's board members have approved the sale of 15% interest in oil refiner Bangchak Petroleum to a state investment fund Vayupak.

Reuters cited PTT chief executive Pailin Chuchottaworn as saying to reporters that the stake sale is expected to fetch THB10bn ($306m).

The divestment is part of PTT’s strategy to sell all of its 27.22% stake in Bangchak Petroleum as the former intends to avoid criticisms from political groups, which allege that PTT has a monopoly in the domestic market.

PTT is a major shareholder in five of six oil refineries in Thailand, reports Bangkok Post.

The company is planning to sell the remaining stake in the oil refiner to any interested investors, Pailin said.

Pailan was quoted by Reuters as saying: "PTT is open to talk with any investors who offer the best proposal. We don’t limit ourselves to two investors which previously offered the prices."

The deal is expected to be completed within the first quarter of 2015.

Bangchak operates a refinery that has a production capacity of 120,000 barrels per day besides running over 1,000 service stations and a solar farm business, reports the news agency.