North Korea test-fired cluster-bomb warheads, its state media reported Sunday, the latest in a slew of weapons drills aimed at training its military units on using them.

The test, conducted on Saturday, came after the nuclear-armed North recently trialled a range of weaponry including attack drones, a new precision-guided torpedo system and an intermediate-range hypersonic missile.

It also came against the backdrop of growing tensions over a landmine explosion along the heavily fortified border between the two Koreas that saw three South Korean soldiers wounded.

The North has denied responsibility and vowed to further fortify its border areas and resume its loudspeaker campaign.

Saturday's test was conducted to "assess adaptation to combat and power of a cluster-bomb warhead to be tipped on tactical ballistic missiles", the official Korean Central News Agency reported Sunday.

Officials said it confirmed the weapon "is capable of turning into ashes a target area of 12 to 13 hectares with its highest-density power".

"Within this year we will enable units to select and use all those types according to operational aims and specific features of targets," said the general director of the North's Missile Administration.

Photos released by KCNA showed a projectile firing from a mobile launcher, with an orange exhaust plume. Another image showed multiple cluster-bomb impacts on an island target.

North Korean leader Kim Jong Un was not present on Saturday, although he had overseen a test-launch of cluster-bomb warheads mounted on a ballistic missile in April, accompanied by his daughter Ju Ae.