SEOUL - NORTH Korea has fired short-range missiles into international waters in the Yellow Sea as part of a routine military exercise, a defence ministry official said on Wednesday.

The missiles were fired on Tuesday, the official told AFP on condition of anonymity, adding the type and number were unclear.

'The latest missile launch was seen as part of routine military exercises,' he said.

Yonhap news agency said two missiles were fired in the first such launch since March.

'North Korea had designated an off-limit zone for vessels in the Yellow Sea before it fired missiles,' it quoted a source as saying.

'It appears to have fired KN-02 or Styx missiles into the international sea from North Korean waters.' The North has carried out short-range missile test-launches many times before.

The latest exercise comes amid intense efforts to save a nuclear disarmament agreement, which is in danger of collapsing because of a dispute over verification of the North's declared nuclear programme.

Chief US nuclear negotiator Christopher Hill visited Pyongyang last week to try to rescue the six-nation deal.

North Korea is bridling at a US-inspired verification plan which reportedly calls for the secretive communist state to give access to undeclared suspected nuclear facilities and to let inspectors take samples of material.

The North has also carried out long-range missile tests in recent years which have alarmed its neighbours.

The communist state test-launched a Taepodong-1 from the Musudan-ri east coast site in 1998 over Japan. It test-launched a Taepodong-2 from the same site in 2006 but the missile failed. -- AFP