The pipeline, owned by Star Petroleum Refining Public Company (SPRC), sprang a leak on Jan 26 and spewed an estimated 47,100 to 55,000 litres of oil into the sea.

It was patched up within a day but not before it damaged a beach area in Rayong province and threatened corals in the shallow waters.

The same pipeline today spilled a further 5,000 litres of oil and the cause of the leak was being investigated, said Attapon Charoenchansa, director-general of the pollution control department told reporters.

Deputy governor of Rayong province, Pirun Hemmarak, said the latest spill was unlikely to reach the shoreline under current tide conditions.

SPRC said it was working with authorities to contain the spill.

The eastern coast is home to several beach destinations popular with foreign tourists.

The spill comes as Thailand sees a steady increase in visitors following the recent easing of its tight entry restrictions and quarantine.