North Korea warned South Korea on Sunday that it would shell islands close to their disputed sea border if the South violates its territorial waters during a military drill reported to begin in the Yellow Sea this week.
The official KCNA news agency also quoted the North's military as urging civilians living on five islands near the disputed area to evacuate before the start of the military exercises on Monday.
The North has repeatedly threatened armed retaliation against the South's military exercises but it is rare for Pyongyang to mention in advance about evacuation of civilians over such drills.
The North's military said that if the South starts a reckless military provocation in those waters, trespassing on the DPRK's inviolable marine demarcation line,.... the KPA will promptly make merciless retaliatory strikes.
DPRK stands for Democratic People's Republic of Korea and KPA for Korean People's Army.
South Korean media last week reported the South Korean and U.S. troops will stage a joint five-day anti-submarine exercise in the Yellow Sea from Monday.
There was no official confirmation of the exercises.
Both Koreas regularly conduct exercises near their disputed maritime border, raising the risk of a miscalculation by either side which could ignite a wider war.
In its warning on Sunday, North Korea said the South should not forget its shelling on the southern island of Yeonpyeong in November 2010, in which four people including two civilians were killed.
The attack on the island was the first on civilians since the end of the 1950-53 Korean War. The North at the time said the South's military drill near the disputed western maritime border triggered its bombardment.
(Reporting by Sung-won Shim; Editing by Sanjeev Miglani)