A peace pact would "lead to putting an end to the US hostile policy toward [North Korea], which spawned the nuclear issue," a spokesman from the North's Foreign Ministry said in a statement on Friday.
Such a move would automatically result in the denuclearisation of the peninsula, the statement said.
The unnamed spokesman, quoted by the North's official Korean Central News Agency, said such a move would "give a strong impetus" to arms talks set to resume on Tuesday in Beijing.
The North said earlier this month it would end its 13-month boycott of the talks - which include China, Japan, Russia, South Korea and the United States - after being reassured by a US envoy that Washington recognised its sovereignty.
Three previous rounds aimed at convincing the North to disarm have failed to resolve the nuclear standoff.
North Korean leader Kim Jong Il has given encouraging signs about prospects for the talks - mentioning to a visiting South Korean cabinet minister last month that the denuclearisation of the peninsula was the dying wish of his father, the North's founding ruler Kim Il Sung who died in 1994.
However, it was not clear if the North's new demand could throw off next week's talks by creating yet another negotiating point to be thrashed out among the six countries.
The North's delegation to the talks, led by Vice Foreign Minister Kim Kye Gwan, departed on Friday for Beijing, KCNA reported.
Kim Jong Il (C) is positive about
talks with South Korea
The North said its new request "presents itself as an issue pending an urgent solution for fairly settling the nuclear issue between (North Korea) and the US."
Separately, the North's Foreign Ministry repeated its demands for diplomatic recognition and a non-aggression treaty with the United States in exchange for giving up its nuclear programme in comments to China's official Xinhua News Agency late on Thursday.
The North also asked to be removed from the US list of countries that sponsor terrorism and that economic sanctions against it be dropped.
Deputy Foreign Minister Song Min-soon, the South's nuclear envoy, said on Friday that all five countries in the talks besides the North "have reaffirmed their will to negotiate seriously and produce substantial and visible results."
However, he acknowledged there were "differences" in their approaches that would have to be discussed during the talks, but declined to elaborate.
"This could be a long process," Song said of finding a resolution to the nuclear standoff.
The United States has refused to give concessions until North Korea is certified as free of nuclear weapons, but the North insists it get something first before abandoning its atomic program.
South Korea said this month it has also offered massive energy aid to the North if it agrees to disarm.
The North alleged on Friday that Washington has for decades stifled efforts to turn the Korean War cease-fire into a lasting peace agreement.
Doing so "is essential not only for the peace and reunification of Korea but for the peace and security in Northeast Asia and the rest of the world," the North's spokesman said.
The 27 July, 1953, ceasefire ending the Korean War established the 4km demilitarised zone that divides the peninsula.
There have been periodic talks since then about establishing a peace treaty, but they have failed to make any progress.
In the absence of a treaty, the two Koreas remain technically at war and hundreds of thousands of troops face off across their border.
Since 2000, the two countries have sought to reconcile as South Korea has pursued a policy of engagement with its communist neighbour to foster reform.
About 32,000 US troops are
deployed in South Korea
About 32,500 American troops are deployed in South Korea as a legacy of the Korean War.
North Korea's current nuclear standoff was sparked in 2002 after US officials accused it of running a secret uranium enrichment programme.
The North has since withdrawn from the Nuclear Non-proliferation Treaty and made moves that would allow it to create more radioactive materials for atomic bombs.
In February, North Korea claimed it had nuclear weapons, but it has not performed any known tests that would confirm its arsenal.