Seoul: North Korea has announced a nine-day ban on shipping off part of its west coast and South Korea is watching for any signs of short-range missile tests, media reports said on Friday.
"We are closely monitoring North Korea`s military activities as it imposed the no-sail zone from June 19-27," a Defence Ministry official told Yonhap news agency on condition of anonymity.
The JoongAng Daily newspaper carried a similar report.
The no-sail zone was declared near the western port city of Nampo, north of the disputed inter-Korean sea border, the official told Yonhap.
The ministry believes the declaration may be in preparation for a regular artillery exercise but is checking whether there are plans for short-range missile launches, the agency said.
The North has frequently test-launched short-range missiles in the past. But tensions are currently high following the sinking of a South Korean warship near the maritime border in March with the loss of 46 lives.
South Korea, citing the findings of a multinational probe, says a North Korean torpedo sank the ship. It is pressing for United Nations Security Council condemnation of its neighbour.
The North denies involvement and threatens a military response to any UN actions.