SEOUL: North Korea appeared to have test-fired a short-range missile into the Sea of Japan on Wednesday as part of a routine military exercise, Yonhap news agency said.

The reported test came at a sensitive time as UN inspectors were to visit the reactor at the centre of North Korea's nuclear programme in their first on-site inspection in nearly five years.

An unidentified government source told Yonhap that the missile with a range of some 100 kilometres (62 miles) appeared to have been fired at 11:30 am (0320 GMT).

"We have secured information on the launch of a short-range missile off the east coast in North Korea's South Hangyong province...the launch was probably seen as part of North Korea's routine exercise," the source was quoted as saying.

South Korean officials refused to confirm the report.

"We are closely watching North Korea but we cannot confirm the report," a spokesman for the Joint Chiefs of Staff told AFP.

It was North Korea's third missile launch this year, Yonhap said.

On May 25 the North test-fired one missile into the sea off its east coast.

There were test-launches of two missiles on June 7, this time into the Yellow Sea on the other side of the peninsula.

The June 7 launches were believed to be of ground-to-ship or ship-to-ship missiles with a range of some 100 kilometres. All landed in North Korean waters.

South Korean officials have played down the significance of North Korean missile launches this year, calling them part of normal military exercises.

But the North's missile launches have heightened tensions in the region in the past decade. In 1998 it sparked alarm in Japan by test-firing a long-range missile over that country.

In July last year it test-fired seven missiles, including its Taepodong-2 that in theory could reach the US west coast. Those launches brought UN condemnation and missile-related sanctions.

Some analysts here say the North, which staged its first nuclear test last October, might be preparing the ground for another long-range missile test. - AFP/yy