North Korea has claimed that it conducted another test of an underwater nuclear weapon.

According to the North's official Korean Central News Agency(KCNA) on Tuesday, the Academy of National Defense Science tested the nuclear underwater attack system from Saturday to Monday.

The KCNA said that the “Haeil-1” underwater nuclear attack drone was deployed off the coast of Wonsan Bay on Saturday afternoon, with the test warhead detonating underwater upon reaching a target off Hwadae County in North Hamgyong Province on Monday morning.

The drone reportedly traveled 600 kilometers for 41 hours and 27 minutes, cruising along a saw blade and elliptical course.

The KCNA again said that the test results verified the reliability and safety of the drone and proved its lethal strike capability.

This follows North Korea's announcement that it conducted a test of a new underwater nuclear attack drone from Tuesday to Thursday, although Seoul's Joint Chiefs of Staff said on Monday that the claims on the drone might have been exaggerated or fabricated.

Meanwhile, the North also confirmed the firing of two short-range ballistic missiles on Monday in a drill simulating tactical nuclear attacks. The KCNA said that in the test, the North detonated a mock nuclear warhead 500 meters above a target islet off Kim Chaek in North Hamgyong Province.