Seoul, April 3 (IANS): North Korea on Friday test-fired four short-range missiles into its western waters, a South Korean defence ministry official said.

The official said by phone that North Korea launched four projectiles, estimated to be short-range missiles, into the western waters from Dongchang-ri in North Pyongan Province between 4.15 p.m. and 5 p.m., Xinhua news agency reported. The projectiles flew about 140 km.

At about 10.30 a.m on Thursday too, North Korea fired one short-range projectile, which seems to be the same kind as those launched on Friday, the official said.

The South Korean military believed that those projectiles were short-range KN-02 missiles given their range, pace and trajectory.

The test-firing came in protest against the ongoing joint annual war games between the US and South Korea and some South Korean civic groups seeking to float anti-North Korea leaflets across the border.

The "Key Resolve" command post exercise ended on March 13, but the "Foal Eagle" field training exercise, which kicked off on March 2, is scheduled to last until April 24.