Oil and clumps of tar were found on a 4-kilometre stretch of Sichon Beach in Nakhon Si Thammarat's Sichon district yesterday.
The carcass of male four-month-old dolphin, weighing 30 kilogram, was also found in the area. The dolphin is said to have been dead for four to five days and the carcass will be sent to the Research Center Lower Gulf of Thailand in Songkhla province.
Sichon district chief Pitak Boripat inspected the affected beach, located between tambons Sao Pao and Thung Prang.
He ordered that the clumps of tar be collected and given to responsible agencies to determine the type of oil and its origin.