Natural Resources and Environment Minister Varawut Silpa-archa has ordered authorities to track down those responsible for the oil slicks and tar balls found on several beaches in Phuket last Friday.
The Department of National Parks, Wildlife and Plant Conservation (DNP) and Department of Marine and Coastal Resources (DMCR) are investigating the source of the slicks seen on Nai Yang, Mai Khao, Nai Thon and Layan beaches on the island's northwest, he said.
Mr Varawut said the actions of irresponsible business operators are threatening to harm the environment, which had just recovered from the negative impact of mass tourism during the Covid-19 pandemic.
State agencies including the Marine Department and Tourism Ministry should urge business operators to conduct themselves responsibly to prevent long-term damage to nature and the country's reputation as a tourist destination.
Puripat Thirakulpisut, deputy director-general of the Marine Department, said authorities believe the slicks were bunker fuel used by marine vessels.
Out of the four beaches affected by the slicks, Mai Khao beach, was the most severely affected, he said, noting the slicks affected a 10-square-kilometre area.
The department will lodge a complaint with police today, so investigators can begin tracking down the offending vessel, said Mr Puripat.
The offenders face a jail term of up to three years, a fine of up to 60,000 baht and they will be ordered to pay for rehabilitation costs, he added.
According to Mr Puripat, the marine office in Phuket is gathering information about vessels passing the western side of Phuket from the Vessel Traffic Service (VTS) system in the Andaman Sea. Authorities launched a big clean-up operation over the weekend.