PTT, Thailand's state-controlled energy company, has signed a memorandum of understanding with the finance ministry to buy a 30 per cent stake in Thai Petrochemical Industries, the country's largest corporate debt defaulter.

As part of the plan, the Government Pension Fund and the state-managed Vayupak Fund will acquire a 20 per cent stake in TPI, while the Government Savings Bank will take 10 per cent.