South Korea and the United Nations Command sent in troops Friday to crack down on illegal Chinese fishing boats in neutral waters around the mouth of the Han River between the two Koreas.

The military operation marks the first of its kind to have taken place in the estuary region, where the Han River meets the Yellow Sea, after its designation as a no man's land in the armistice agreement following the 1950-53 Korean War.

Seoul recently formed a 24-strong military police team with four speed boats to combat an increasing number of Chinese vessels illegally coming to and fishing in the neutral waters, a military buffer zone, said an official at the defense ministry.

"The troops carried out their first crackdown operation in the estuary area earlier in the day," a military official told reporters.

He said the operation marks the first time South Korea and the United States-led UNC stationed in the country have taken joint action to drive out foreign vessels in the military buffer zone.

Illegal Chinese fishing has soared in the area since last year.

Until 2014, illegal Chinese fishing in the area was scarce, with only two to three incidents being reported every year. This number shot up to about 120 last year, and in the first five months of 2016 Chinese fishing boats have already been detected on around 520 occasions, the ministry official said.

No Korean or foreign ships are allowed to sail in the area except those that are officially registered with the military armistice commissions of either South or North Korea, according to the armistice agreement's annex governing civil shipping in the neutral waters.

The subsidiary agreement allows each side to deploy a maximum of four patrol boats and 24 military police officers armed with pistols and rifles in the region to maintain order and enforce the law.

In accordance with the agreement, the South Korean crackdown team has been staffed with military policemen and coast guard officers, translators and members of the UNC commission. They will also flew UNC flags from the four rigid-inflatable boats, according to the ministry official.

The personnel have been authorized to use force against Chinese fishing boats if they do not comply with an initial verbal warning to leave, the official said. South Korea will have warships and choppers standing nearby to be deployed in the event of any skirmishes that could take place with North Korea in the process of the crackdown operations, he also said.

On Wednesday, the South Korean armistice commission notified North Korea of the crackdown plans, the official also added. In efforts to prevent a diplomatic row with China, South Korea informed its larger neighbor of the operation in advance.

"Despite our government's multifaceted diplomatic efforts, illegal fishing by Chinese boats has continued to the extent (that South Korea) has come to realize its diplomatic measures have reached their limits," the official said. "Under this view, South Korea decided to launch its troops in cooperation with the UNC."

He then said the crackdown operations will be carried out in accordance with the armistice agreement with North Korea.

Another government official said, "South Korea determined that a more effective crackdown and control is needed in the area at a time when illegal Chinese boats could drain marine resources in the estuary of the Han River and lead to possible military clashes between South and North Korea."

"Gen. Vincent K. Brooks, UNC commander, in accordance with his responsibilities under the Armistice Agreement, authorized the UNC operation to enforce restrictions on fishermen in the Han River Estuary," the UNC said in a statement. (Yonhap)