South Korean coast guards have launched a massive crackdown on illegal fishing in the Yellow Sea and apprehended at least 21 Chinese fishing vessels, South Korean media reported, citing coast guard officials.

The Global Times contacted the Chinese consulate-general in Gwangju in southwestern South Korea, and an official said by phone that he has "no further details to release" and declined to comment on whether they have attempted to reach out to South Korean authorities.

The Yonhap News Agency said the South Korean authorities mobilized around 30 coast guard vessels, accompanied by planes, choppers and special police, in this round of massive crackdowns against illegal fishing by Chinese boats.

The concentrated crackdown, which was launched Wednesday and ended Friday, had detained 21 Chinese vessels as of Thursday.

The Dong-A Ilbo newspaper said South Korean naval forces also took part in the operation that covered sea areas from Taean to Jeju Island.

China and South Korea in 2000 signed a fishery agreement, which marks common fishing areas and requires that a country's boats must obtain a permit to fish in the other country's waters.

Despite this, China and South Korea have had a string of unpleasant incidents related to illegal fishing in recent years.

The latest clash between Chinese fishermen and the coast guard occurred in waters near the port city of Incheon on November 27. Four South Korean coast guards were injured during the confrontation and 24 Chinese sailors were arrested.

In September, a Chinese fisherman named Zhang Shuwen died when a rubber bullet fired by coast guard officers hit him in the heart.

While the South Korean officers accuse Chinese fishermen of being violent in resisting law enforcement, Chinese fishermen complain that the maritime police often resort to force.

Agencies contributed to this story