Seoul on Thursday rejected North Korea's fresh demand for verification that all US nuclear weapons have been withdrawn from South Korea, saying there are no such weapons on its territory.
The North made the demand on Tuesday in a foreign ministry statement seen as its first message to the incoming US administration of Barack Obama.
The communist state, which has committed itself to nuclear disarmament under a February 2007 six nation pact, called for "free field access" to ensure there are no such weapons in the South.
Washington and Seoul say US atomic weapons were withdrawn from South Korea in 1991.
The South's foreign ministry accused North Korea of "distorting the substance of the situation." It called for the North's active cooperation to denuclearise the peninsula.
In its on Tuesday statement the communist state also vowed not to give up its nuclear weapons until the United States drops its "hostile" policy and establishes diplomatic relations.
Pyongyang's comments reaffirmed current policy but came just days before the Obama administration takes power.
"There will be no such case in 100 years' time that we will hand over our nuclear weapons first without the fundamental settlement of the US hostile policy toward Korea and its nuclear threat," the statement said.
The 2007 pact calls, in its final phase, for the scrapping of the North's nuclear weapons and stockpiled material in return for aid, normalised relations with the United States and Japan and a formal peace agreement on the Korean peninsula.
The North is disabling its nuclear plants at Yongbyon under an interim phase of the pact but negotiations have not started on the final leg.
The US says the North must scrap its nuclear weaponry before diplomatic relations are forged.
The six nation talks group the two Koreas, the US, China, Russia and Japan.
Despite its latest uncompromising statement, the North has invited a South Korean team to visit Yongbyon to consider the possible purchase of 14,000 unused reactor fuel rods.
Seoul's foreign ministry said the team, led by deputy chief nuclear negotiator Hwang Joon Kook, was scheduled to arrive in the North early on Thursday evening.
Analysts saw the visit as a positive sign the North remains interested in completing the disablement.
South Korea has expressed interest in buying the rods for use at its nuclear power plants.