North Korea stepped up its rhetoric against the South Wednesday, warning that its neighbour would face a "most miserable end" if it joined the US in "a war of aggression" against Pyongyang.

The threat follows a series of North Korean missile tests, reflecting escalating military tensions on the divided peninsula ahead of large-scale US-South Korea military drills next month.

"The South Korean authorities will not be able to escape the most miserable end if they persistently join the US moves for a war of aggression," the North's Committee for the Peaceful Reunification of Korea said in a statement published through state media.

"If the South Korean warmongers offer cannon fodder for a US war of aggression against the DPRK (North Korea), South Korea will also be the target of our retaliatory strikes," it said.

The North also has access to "precision and diversified nuclear strike means" designed to target the US in the event of a war, the statement claimed.

On Sunday the North test-fired five short-range missiles into the sea, the day after it had trumpeted the test of a new "ultra-precision" anti-ship cruise missile under the watchful eye of leader Kim Jong-Un.

Next month sees the launch of annual joint exercises by the US and South Korean military, which regularly see North-South relations go into a vertiginous tail-spin.

Pyongyang views the drills as provocative rehearsals for invasion, while Seoul and Washington insist they are defensive in nature.

Last month, North Korea offered to suspend any further nuclear tests if this year's joint exercises were cancelled -- a proposal the US State Department described as a "non-starter".

North Korea has conducted three nuclear tests -- most recently in February 2013 -- and its moratorium offer was seen in Washington as an "implicit threat" to carry out a fourth.

Last week the North's top military body ruled out resuming dialogue with the "gangster-like" US, and vowed to respond to any US aggression with nuclear strikes and cyber warfare.