"North Korea fired an unidentified projectile eastward," Seoul's Joint Chiefs of Staff said in a statement, without giving further details.

Pyongyang carried out an unprecedented seven weapons tests in January, including of its most powerful missile since 2017, when leader Kim Jong Un baited then-US president Donald Trump with a spate of provocative launches.

Last month Pyongyang said it had carried out a test of "great significance" towards developing a reconnaissance satellite, a day after Seoul said it had detected a ballistic missile launch.

The North's latest testing comes at a delicate time in the region, as South Korea gears up to elect its next president on Wednesday.

Experts say Pyongyang could use its next key anniversary -- the 110th birthday of founding President Kim Il Sung on April 15 -- to carry out a major weapons test.