North Korea Friday blasted an upcoming nuclear security summit in Seoul as an "unsavoury burlesque" intended to justify an atomic attack by South Korea and its US ally.

In the second such broadside in two days, it also accused Seoul's ruling conservative party of using the event to improve its image before parliamentary elections in April.

South Korea says next month's summit, to be attended by US President Barack Obama and about 40 other world leaders, will focus on ways to safeguard atomic material worldwide and prevent acts of nuclear terrorism.

Seoul officials have said North Korea's nuclear programme is not on the agenda but the summit may build momentum towards denuclearisation.

Pyongyang's main newspaper Rodong Sinmun said the South's aim in hosting the 26-27 March event "in league with the US" is clear.

"It is designed to make the already bankrupt theory of 'nuclear threat from the north' sound real and justify their nuclear racket and moves to ignite a nuclear war against the DPRK (North Korea)," the paper said.

The commentary was issued while US-North Korean talks were underway in Beijing. The two sides were discussing a possible resumption of six-nation talks on scrapping the North's nuclear programme.

The summit would be "an unsavoury burlesque" staged by the US and the South Korean ruling party "in conspiracy" against North Korea, the Rodong Sinmun said.

"If substantial nuclear security and peace are to be achieved in the peninsula, it is necessary to put an end to the nuclear war threat from the US and the South Korean warlike forces."

The North frequently says it needs atomic weaponry to counter a nuclear threat from the US, which has 28,500 troops stationed in the South.

The US withdrew atomic weapons from South Korea in 1992 but offers to extend a "nuclear umbrella" over its ally in case it comes under atomic attack.

Rodong Sinmun said the South's conservative government, "after being cursed and forsaken by the people", was trying to use the summit to improve its image before the 11 April election.

President Lee Myung-Bak this week accused the North of trying to incite divisions within the South to sway the vote but said the tactic would not work.