COLOMBO, Sri Lanka—Fishermen using illegal nets are suspected of killing dozens of dolphins that were found this week off Sri Lanka's northwest coast.

Sayuru Samarasundara, head of Sri Lanka's National Aquatic Resources Research and Development Agency, said Thursday that the dolphins were killed after they became stuck in a type of net that is banned in the area. He said police had arrested two people suspected of using the illegal nets.

Samarasundara said he saw eight dead dolphins, but local media reports say at least 42 dead dolphins were found Tuesday.

Kapitiya, the area where the dead dolphins were found, is a popular tourist destination famous for dolphin watching. Sri Lanka's Fisheries Ministry has said it will not tolerate any illegal fishing methods in the area.