Another oil spill was detected in the Gulf of Thailand off the coast of Rayong province on Thursday and was being cleaned up, according to local authorities.
An estimated 5,000 litres of oil had leaked and nine naval ships had been deployed to contain the slick, which was about 20 kilometres from the shore, said deputy provincial governor Pirun Hemarak.
Mr Pirun said he did not expect the slick to reach land and the situation was under control.
On Thursday, Pollution Control Department director-general Athapol Charoenshunsa said Star Petroleum Refining Public Company Limited (SPRC) alerted authorities to the latest leak, which may have occurred during modification work on an underwater pipeline.
An investigation was ongoing to determine the cause.
The department initially refused the company's request to use about 5,000 litres of dispersant, deeming the amount excessive. However, an unspecified amount was later dispatched to the area via the First Naval Area Command, in a bid to contain the oil spill.
On Jan 25, an underwater pipeline belonging to SPRC broke near Map Ta Phut in Rayong. The spill, involving 47,000 litres of crude oil, had since been cleared up.