North Korea's military accused the United States and South Korea Friday of trying to topple the Pyongyang regime and said it was ready to launch nuclear attacks to frustrate any provocations.

The military General Staff cited a South Korean newspaper report as evidence of "desperate moves of the US imperialists and the South Korean puppet warmongers" for regime change.

"Those who seek to bring down the system in the DPRK (North Korea)... will fall victim to the unprecedented nuclear strikes of the invincible army," a General Staff spokesman told the official Korean Central News Agency.

Dong-A Ilbo on March 19 said representatives of the US Pacific Command and state defence think-tanks from South Korea and China would meet in China next month to discuss controlling weapons of mass destruction in case of regime collapse in Pyongyang.

There has been no confirmation of the report.

The North has previously threatened nuclear attacks in response to what it calls plots for regime change -- an especially sensitive topic given leader Kim Jong-Il's age and health.

Kim, 68, suffered a stroke in August 2008 and is widely reported to be preparing to hand over power eventually to his youngest son.

The head of a South Korean think-tank said this week that Kim is also suffering from kidney failure, which requires dialysis.

The military described the North's communist system as an "impregnable fortress" and described expectations of regime collapse as "a pipe dream of a lunatic wishing for the sky to fall".

It said its army and people would bolster the nuclear deterrent "capable of frustrating any plot and provocation at a single strike".

The North is suffering severe food shortages, exacerbated by a bungled currency reform last November that sparked rare public unrest.

A study published Wednesday by the US East-West Center, based on information from refugees, found the regime was increasingly unpopular at all levels.

Efforts are continuing to bring Pyongyang back to the six-nation nuclear disarmament talks, which it quit in April 2009.

As preconditions, it demands a lifting of UN sanctions that have hit its hard currency earnings and a US commitment to hold talks about a formal peace treaty.