IBTimes UK

South Korean ships chased away Chinese fishing boats which were illegally harvesting highly valued blue crabs from an area close to Seoul's disputed sea boundary with North Korea on Friday.

The operation started with four naval and marine boats in neutral waters to drive away 10 Chinese boats around South Korea's Ganghwa island.

An official from Seoul's Defense Ministry cited the office rules and said that the United Nations Command, which governs the zone of prohibited fishing activity, has approved the operation. However, the official did not want to be named.

"United Nations Command takes its responsibility to maintain the armistice very seriously. We had a responsibility to act and we are doing that," Gen. Vincent Brooks, the US commander of the United Nations Command, told The Associated Press.

The Seoul official said that both China and North Korea governments were notified about this operation before it began. But he refused to reveal the details of the planning process to repel the ships and other information about the operation.

Recently, South Korean fishermen dragged two Chinese fishing boats and handed them over to local the South Korean authorities. The fishing boats were found catching crabs in the southern area of the sea boundary with North Korea.

In response, North Korea said that South Korean fishing and naval vessels had invaded their territory.

Seoul had asked Beijing to take strict measures against the illegal fishing by Chinese boats in South Korea-controlled waters. The issue has in recent years soured the relationship between the two neighbours.

According to the Ministry of Oceans and Fisheries, last year, South Korean authorities seized about 600 Chinese vessels for illegal fishing and more than 100 this year till May. Most of these boats were caught from waters off the western coast of South Korea.

In October 2014, China expressed anger when the captain of a Chinese fishing vessel was shot and killed by a South Korean coast guard. The Chinese captain had resisted the inspection of his ship for suspected illegal fishing. While, in 2011, a South Korean coast guard officer was killed in a clash with Chinese fishermen in South Korean waters.

IBTimes UK