North Korea has fired shells into waters near a South Korean warship on patrol south of the disputed Yellow Sea border, prompting an evacuation of residents on a nearby island, officials said.
Two shells fell near the South Korean ship, which was sailing near the frontline island of Yeonpyeong on Thursday, the South’s defence ministry said.
Residents on the island were advised to move to civilian shelters and nearby fishing boats were told to return to port.
North Korea shelled Yeonpyeong in November 2010, killing four South Koreans, briefly triggering concerns of a full-scale conflict.
“North Korea fired shells which fell near our ship, but it did not cause any damage to our ship,” a ministry spokesman told AFP.
The North’s move began at 6pm local time (1900 AEST), prompting a response from the South Korean vessel which fired several rounds into waters near a North Korean vessel, he said.
The exchange of fire sparked a tense confrontation between the two sides, but there was no additional provocation from North Korea, the spokesman said.
“The situation is now stable, but we are closely watching the movement of North Korean troops,” another ministry official said.
The defence ministry sent a message of protest to North Korea through a military hotline, he added.
There were no reports of casualties or damage on the island from authorities, the Yonhap news agency said.
The North’s military on Wednesday had threatened to attack South Korean warships “without any warning” if there was even a “trifle” violation of the maritime border.
The North does not recognise the Yellow Sea border, the scene of brief but bloody naval clashes in 1999, 2002 and 2009.
In March the North fired hundreds of shells in a live exercise near the sea boundary. About 100 shells dropped into South Korean territorial waters, and the South responded with volleys of shells into North Korean waters.
Cross-border tension has been high for months, amid signs that the North may be preparing to conduct a fourth nuclear test.