Allen & Overy (A&O), Baker & McKenzie and Latham & Watkins have all taken roles on a $1bn (£636m) bond issuance by Thai Oil, one of the largest petroleum refineries in Thailand.

The publically-listed refining and petrochemical company, which is owned by Thailand's PTT Group, issued a dual tranche of senior unsecured fixed-rate notes to foreign institutional investors earlier this month.

Bakers acted for Thai Oil, with a team of three led by Bangkok capital markets partner Viroj Piyawattanametha.

Meanwhile, magic circle firm A&O advised the underwriting banks, which included Barclays, HSBC and Standard Chartered. Hong Kong corporate partner and Asia capital markets head James Grandolfo led a team of lawyers in Hong Kong and Bangkok.

Latham served as US counsel for Thai Oil, fielding an Asia corporate team overseen by partners Michael Sturrock and Timothy Hia in Singapore. This is the second time the duo have represented a division of Thailand's PTT Group on a major international bond offering in the last six months, after advising on a bond offering for PTT Global Chemical Public Company last September.

Elsewhere, Latham Los Angeles partner Sam Weiner led a team from the firm advising on tax aspects of the deal.

The deal reportedly marks Thai Oil's return to the international bond market after almost eight years. Proceeds from the offering are set to be used for general corporate purposes, working capital, capital expenditures and refinancing.