A Japanese daily says North Korea has proposed a peace treaty with the United States which would replace the 51-year-old Korean War armistice.

Quoting government officials in Washington and Pyongyang, the Asahi Shimbun newspaper said the North proposed that the two Koreas and the United States sign a peace treaty and have it later endorsed by China, Russia and Japan.

But the reports said the proposal calls for such a treaty to be negotiated only between the United States and North Korea and signed before the dismantlement of Pyongyang's nuclear weapons program and possible arms reduction talks.

The paper did not say when North Korea made the proposal, but called it "unprecedented" since it represents a significant change in Pyongyang's longstanding insistence that any peace treaty be signed only with Washington.

The reports said that Washington has rejected the North's proposal, saying that negotiations for a peace treaty should be conducted along with talks on establishment of diplomatic relations, and normalization of diplomatic ties is not possible without the resolution of the nuclear standoff.

The Korean War ended in an armistice signed between North Korea and the United States in 1953, leaving the Korean Peninsula still technically at war.