South, North Korean ships exchange warning shots

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

The incident took place around 9:50 a.m. near the oft-contested border island of Yeonpyeong, when the North Korean patrol boat crossed into the South's water, a ministry spokesman said.

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

The official said there have been no reports of injuries and damage to the ships of either side. He added the North Korean ship was in South Korean–controlled waters for about 10 minutes before it retreated to its waters. He requested anonymity citing official policy.

The latest exchange followed the surprise visit to South Korea on Saturday by top ranking aides to North Korean leader Kim Jong Un.

It was led by Hwang Pyong So, a newly elected vice chairman of the nuclear armed North's powerful National Defense Commission, who is widely thought to be Kim's No. 2.

The visit resulted in an agreement to resume a high-level dialogue that had been suspended for seven months as military tensions escalated on the divided peninsula. South Korea has been highly critical of North Korea's nuclear and missile programs, including recent rocket and missile tests and apparent preparations for a fourth nuclear test.

The sea border and Yeonpyeong have been the scene of clashes in the past that killed scores of sailors on both sides, with North Korean vessels frequently crossing the Northern Limit Line. The de facto maritime boundary is not recognized by Pyongyang, which argues it was unilaterally drawn by U.S.-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, killing four South Koreans, two of them civilians, which briefly sparked concerns of a full-scale conflict. Instead, the attack led to the South cutting off all political and commercial exchange with the North except for a factory zone in the North Korean city Kaesong, where South Korean companies operate manufacturing facilities

The news of the latest military activity also comes as speculations of North Korean leader Kim Jong Un's health mount with his absence from public view for more than a month.

Al Jazeera with wire services