The firing exercises are an apparent reference to the suspected barrage of ballistic missile test-launches that South Korea said North Korea conducted on Thursday.

Experts say North Korea's large-sized artillery rockets blur the boundaries between artillery systems and short-range ballistic missiles because they can create their own thrust and are guided during delivery.

The North's Korean Central News Agency reported its latest weapons tests are meant to demonstrate North Korea's resolve not to hesitate to launch a preemptive strike on South Korea, if threatened. It cited Kim as saying that the drills “will serve as an occasion in clearly showing what consequences our rivals will face if they provoke us".

KCNA accused South Korea of staging a “clumsy counteraction of dangerous armed demonstration against the exercise of legitimate sovereign right” of North Korea.

That refers to a South Korean aerial exercise performed hours before North Korea's failed spy satellite launch on Monday night. If successful, North Korea would have placed its second spy satellite into orbit.

The multiple rocket launchers are one of North Korea's main weapons systems targeting South Korea. North Korea says weapons fired from the launchers can carry tactical nuclear warheads.

Photos released by state media showed Kim watching from a distance at least 18 projectiles soaring after being fired from launch trucks. South Korea's military earlier said North Korea fired about 10 suspected ballistic missiles toward the sea off its east coast.

North Korea's failed spy satellite launch drew strong condemnation from the US, South Korea and others because the UN bans any satellite launches by North Korea, viewing them as covers for testing missile technologies. North Korea maintains it has the rights to launch satellites and test missiles.

In recent years, North Korea has been engaged in a run of weapons tests to bolster its nuclear capability to cope with what it calls intensifying US military threats. Foreign experts say North Korea would eventually aim to use a bigger nuclear arsenal to wrest greater concessions from the US when diplomacy resumes.