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 March 26-27 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 April 11 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.

Speaking to reporters as he arrived at London Heathrow airport, where he was taken into custody by US marshals, Christopher Tappin protested his innocence and said he should have been tried in Britain.

US prosecutors accuse the 65-year-old of attempting to unlawfully export batteries for surface-to-air missiles, which were allegedly due to be shipped from the US to Tehran via the Netherlands.

Tappin fought a lengthy battle through the British courts against his transfer to the United States, where he could face 35 years in jail, but lost a final appeal to the European Court of Human Rights last week.

Accompanied to Heathrow by his tearful wife Elaine, Tappin said he was "not very confident at all" about the outcome of his case.

"If I wanted anything, it was to be tried in the UK, not in America, because the Americans have never had to produce one piece of evidence," he said.

His lawyer Karen Todner later said: "Mr. Tappin has been taken now by British extradition officers to the aeroplane, where he is going to be handed over to US marshals.

"He will be arriving in El Paso (Texas) this afternoon. He will be appearing in court on Monday morning, so he will be in custody over the weekend."

The British media have highlighted Tappin's case as an example of what many view as the unequal extradition arrangements with the US.

Critics says US authorities have to provide far less information about an alleged crime to secure the extradition of a Briton than British authorities must provide to extradite an American.

Prime Minister David Cameron said this week that ministers would carry out a review of the arrangements, but said a recent report had found no need for fundamental reform of the system.

Tappin has argued that he was caught up in a US customs sting.

He has said he believed he was exporting batteries for the car industry in the Netherlands, although US authorities say he also told customs officials his shipments were destined for an oil company in Norway.