South Korea launched an operation Friday to drive out illegal Chinese fishing boats from neutral waters close to the disputed sea border with the North, in a move that could further escalate cross-border tensions.

The patrol is the first military operation in the buffer zone -- an effective no-man's land at sea -- between the two Koreas since the area was drawn up at the end of the Korean War in 1953.

Seoul has repeatedly complained to Beijing about the number of illegal Chinese trawlers fishing in the waters.

But the number of Chinese boats in the neutral waters of the Han River estuary and around the disputed sea border in the Yellow Sea has continued to surge in the absence of patrols.

"Diplomatic efforts have met their limits... We've decided to enforce restrictions in cooperation with the UNC," a South Korean military official said according to Yonhap news agency, referring to the US-led United Nations Command (UNC), which oversees the armistice that ended the 1950-53 Korean War.

"The troops carried out their first crackdown operation in the estuary area earlier in the day."

The personnel have been authorised to use force against Chinese fishing boats if they do not comply with verbal warnings to leave, the official said.

South Korea has warships and helicopters on standby, which will be deployed in the event of any skirmishes with North Korea, he added.

The was no immediate reaction from Pyongyang to the rare military patrols.

The UNC had informed the North and China of the military operation before it began.