SEOUL: North Korea has announced a ban on shipping off part of its west coast and South Korea is watching for any signs of missile tests, the defence ministry in Seoul said Friday.

"The move is seen as part of a routine exercise by North Korean troops, but we are closely monitoring their activities," a spokesman told AFP.

The ministry delinced to confirm a report by Yonhap news agency that the no-sail zone was declared from June 19-27 near the western port city of Nampo, north of the disputed inter-Korean sea border.

It is unclear whether the declaration was in preparation for an artillery exercise or missile launches, the Joint Chiefs of Staff said. "We have yet to detect any signs of preparations for missile launches," a spokesman said.

The North has frequently test-launched short-range missiles in the past. But tensions are running 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 and is pressing for UN Security Council condemnation of its neighbour.

The North denies involvement and threatens a military response to any UN actions.

BDST:948 HRS, June 25 2010
NJ/DC