The chief executive of IRPC, Pailin Chuchottaworn, has been appointed successor to Prasert Bunsumpun as CEO of PTT, Thailand's biggest listed company.

The company's board approved the appointment after four candidates were put forward by a selection committee, Naris Chaiyasoot, acting chairman, told a news conference after a board meeting on Friday.

The succession at state-controlled PTT has been closely followed by the market after several years of success under Prasert's management.

After 30 years' service, Prasert will end his second four-year term at the top of PTT in September.

Pragmatic Prasert is highly respected in the industry for his role in restructuring PTT's bureaucratic management and diversifying from oil and gas into coal and other energy-related businesses while helping PTT expand rapidly.

Other candidates had included PTT Chief Financial Officer Tevin Vongvanich and Surong Bulakul, chief executive of the country's largest oil refiner, Thai Oil. The market had seen Surong as a front-runner.