South Korea's military police and Coast Guard are considering extending the crackdown on illegal Chinese fishing in neutral waters around the mouth of the Han River for the third consecutive day on Sunday, officials said, as additional Chinese fishing boats are exiting the sensitive area near the inter-Korean maritime border.

The Coast Guard said it seized a 50-ton Chinese boat that allegedly caught 45 kilograms of crabs in waters off Yeonpyeong Island, a South Korean territory near the inter-Korean border in the Yellow Sea, on late Saturday afternoon and put its seven sailors under arrest.

Amid the intensive crackdown launched on Friday by the South Korean military police, Coast Guard and United Nations Command Military Armistice Commission, there are still about 10 Chinese boats around the mouth of the Han River, officials said.

South Korea recently formed a crackdown team of four vessels with 24 military and Coast Guard forces and UNC Military Armistice Commission personnel as illegal Chinese fishing has soared in the sensitive border areas. From Friday, the crackdown team entered the neutral waters where the estuary of the Han River meets the Yellow Sea. It is South Korea's first joint crackdown operation with the UNC since the border areas were declared a no man's land in the armistice which ended the 1950-53 Korean War.

The armistice's annex governing civil shipping in neutral waters says no Korean or foreign ship is allowed to enter the area except those that are officially registered with South or North Korea.

"A number of illegal Chinese fishing boats have left the area yesterday following our crackdown team's operation," an official from the South Korean military said Sunday on condition of anonymity. "There are only around 10 boats in the area."

When the crackdown team initiated the operation, there were more than 20 illegal fishing boats in the neutral waters. Military officials have said the operation will continue until the last Chinese fishing boat leaves the Han River estuary, but they have yet to resume action on Sunday because the Chinese fishing boats are now staying near North Korean shores.

Under the armistice, the crackdown team cannot go near the North Korean coast. The military official said that the North's military has yet to make special movements on these fishing boats.

"We will consider whether to resume our operation today after considering the movements of Chinese fishing boats and weather conditions," the official said.

June is a high season for catching blue crab in the largely untouched fishing ground, tempting Chinese fishermen to intrude into the militarily sensitive border areas between the Koreas. In the five months of 2016, Chinese fishing boats have been detected fishing in the neutral waters on around 520 occasions, according to the Ministry of National Defense.

After the operation kicked off, China pledged cooperation with South Korea to stop illegal fishing, saying that Beijing respects international treaties on fishing and the local laws of the countries where its fishermen operate. (Yonhap)