About 50 tonnes of oil found on Bang Saen and two adjacent beaches in Chon Buri has now been removed, following a clean-up organised by the Sean Suk Municipality.
The origin of the oil, discovered on Thursday night, remains unknown, but it is thought to have come from vessels offshore involved in an oil transfer. Officials are now reviewing satellite images to try to find out where the oil came from.
Parts of Bang Saen are still showing traces of oil and the beach will remain closed to tourists for the time being. Oil samples have been submitted for lab tests, but it will take 10 days to determine where it came from. The municipality has filed a complaint to police about the incident.