SEOUL (AFP) - North and South Korean naval patrol boats briefly exchanged fire on Tuesday near their disputed Yellow Sea border which has been the site of numerous clashes in the past, the South's defence ministry said.

The incident coincided with raised hopes of a constructive reboot in strained inter-Korean relations following the surprise visit of a top-ranking North Korean delegation to the South just three days before.

The defence ministry said the North Korean vessel had penetrated half a nautical mile into the South's territorial waters.

"Our side fired back when the North Korean patrol boat opened fire," a ministry spokesman said, adding there was "no damage" sustained on the South Korean side.

The incident took place around 9.50am (0050 GMT) near the South Korean border island of Yeonpyeong, the spokesman said, adding that the North patrol boat retreated to its side of the border 10 minutes later.

The maritime boundary, which was unilaterally drawn by the US-led United Nations forces after the 1950-53 Korean War, was the scene of brief but bloody naval clashes in 1999, 2002 and 2009. The Korean conflict ended in an armistice instead of a peace treaty, and technically the two Koreas are still at war.