South Korea called on China to prevent illegal fishing in South Korean territory after its coast guard fired warning shots at Chinese finishing vessels, the country's state-run media Yonhap reported Thursday.

The South Korean coast guard claimed Tuesday it discovered two Chinese fishing vessels illegally fishing off South Korea's shores in the Yellow Sea. When it approached the crafts, about 20 to 30 other similar boats reportedly surrounded the coast guard's patrol boats and threatened to ram into them. The coast guard responded by opening fire with an M60 machine gun, causing the other boats to scatter and flee. No injuries or damages were reported.

"The safety of our own Coast Guard members was at risk," coast guard spokesperson Lee Dae-haeng told Reuters.

The coast guard then apprehended the two vessels, bringing them as well their captains and around 20 crewmembers to the western port city of Incheon for questioning. South Korean authorities were preparing to open an investigation into the incident.

In response, China expressed Wednesday its dissatisfaction with the actions of the South Korean coast guard. Hua Chunying, a spokesperson for the Chinese foreign ministry, pledged to "strengthen the management and discipline" of Chinese fishermen, but condemned what the ministry believed to be a show of excessive force with "destructive weapons."

RTSRPN8 Chinese fishing boats captured by South Korean coast guard are seen at a port in Incheon, South Korea, Oct. 10, 2016. Illegal Chinese fishing in South Korean waters has been an ongoing issue between the two nations. Photo: Reuters

South Korea, however, did not accept this interpretation and reiterated past calls for China to crackdown on its citizens' practice of illegal fishing in South Korean territory as well as their violent resistance to arrest. 

"We cannot accept China taking issue with our Coast Guard's law enforcement methods including the use of such crew-served weapons," South Korean foreign ministry spokesperson Cho June-hyuck said Thursday during in a press briefing.

Illegal Chinese fishing has been an ongoing issue between South Korea and China. The incident comes after South Korean authorities pledged more strict measures, including the use of firearms against Chinese fishing boats caught fishing off South Korea's shores. On Oct. 7, Chinese fishing vessels rammed and sank a 4.5-ton coast guard ship attempting to arrest them. South Korean authorities killed three Chinese fishermen in September by throwing flash grenades in into a room in which they were hiding.

Tensions between China and South Korea remain high over the U.S.' decision to install the Terminal High Altitude Air Defense (THAAD) missile platform in South Korea. The U.S. insists the system is designed to prevent an attack from North Korea, but China claims it threatens its own national security.