North and South Korean naval patrol boats have briefly exchanged fire near their disputed maritime border, according to the South's defence ministry, which said the North's vessel had violated the boundary.

The incident took place about 9:50am (00:50 GMT) on Tuesday near the South Korean border island of Yeonpyeong, when the North Korean patrol boat crossed into the South's water, a ministry spokesman told AFP news agency.

"Our side fired back when the North Korean patrol boat opened fire," he said. "There was no damage."

The area has been the scene of clashes in the past that killed scores of sailors on both sides, with North Korean vessels frequently crossing the so-called Northern Limit Line.

The de-facto maritime boundary is not recognised by Pyongyang, which argues it was unilaterally drawn by US-led United Nations forces after the 1950-53 Korean War.

The Korean conflict ended in an armistice instead of a peace treaty, and technically the two Koreas are still at war.

Both sides complain of frequent maritime incursions by the other and there were limited naval clashes in 1999, 2002 and 2009.

In November 2010, North Korea shelled Yeonpyeong island, killing four South Koreans and briefly triggering concerns of a full-scale conflict.

The latest exchange followed the shock visit to South Korea on Saturday by some of North Korean leader Kim Jong-Un's closest aides.

It was led by Hwang Pyong-So, a newly elected vice chairman of the nuclear armed North's powerful National Defence Commission, who is widely seen as Kim Jong-Un's number two.

The visit resulted in an agreement to resume a high-level dialogue that had been suspended for seven months as military tensions on the divided peninsula soared.

The news also comes as speculations of North Korean leader Kim Jong-Un's health mount, with him being absent from the public for more than a month.