Maritime police in the southwestern port city of Mokpo said Saturday they have seized five Chinese fishing boats on suspicions of poaching in South Korean waters.

Mokpo maritime police seized the five boats in waters some 25 kilometers southwest of the island of Gageo, off the country's southwestern coast, at around 6 p.m. Friday.

The boats were caught using fishing nets with smaller-than-permitted mesh size to catch 4.3 tons of fish inside South Korea's exclusive economic zone, police officials said.

The police are at the scene to investigate whether the boats were also involved in other illegal activities.

Chinese fishing boats are frequently caught fishing in South Korean waters, sometimes leading to violent clashes with South Korean maritime police. (Yonhap News)