SEOUL, South Korea — South Korea demanded yesterday that North Korea abandon any atomic weapons development, but Northern negotiators in Pyongyang stonewalled the nuclear discussion, calling it a matter between North Korea and the United States.

Chief North Korean delegate Kim Ryong Song refused to confirm a claim made during talks last week with U.S. and Chinese officials in Beijing that North Korea is making nuclear weapons, and instead sought to steer yesterdays Cabinet-level talks toward inter-Korean economic projects, Seoul officials said.

Washington believes North Korea has one or two atomic bombs and may be trying to make more. The North has disputed that claim, saying its nuclear program is meant to generate much-needed electricity.

Possession of nuclear weapons would be a “serious violation” of a 1992 inter-Korean agreement to keep the peninsula nuclear-free, South Korean Unification Minister Jeong Se-hyun reminded North Korea, according to South Korean government spokesman Shin Eun-sang.

“We made it clear that we can never accept North Korea’s possession of nuclear weapons,” Shin said yesterday, according to South Korean pool reports from Pyongyang. “We emphasized that the North should dismantle nuclear weapons, if it had any, as well as its nuclear facilities.”

Jeong is leading a five-member South Korean delegation to Pyongyang in the first high-level talks between the Koreas since President Roh Moo-hyun took office in February. Foreign journalists were not allowed to cover the event.

Seoul officials were encouraged by the North’s willingness to hold the talks after canceling previous Cabinet-level meetings earlier this month.

But North Korea remained defiant, saying in its official Rodong Sinmun newspaper that it would arm itself with “a physical means of deterrence” if Washington refused to sign the nonaggression treaty it seeks.

Pyongyang, which President Bush has dubbed part of an “axis of evil” with Iran and prewar Iraq, has accused the United States of planning an invasion after the war in Iraq is over.

“If Washington does not give us a legal guarantee that it will not take military actions, including use of nuclear weapons, against us, we have no other option but to do everything possible for our self-defense,” Rodong said.

The Bush administration has ruled out such a treaty, but U.S. officials have said some form of written security guarantee could be possible.

The three-day inter-Korean talks in Pyongyang, on the heels of the Beijing discussions, come amid renewed tension over North Korea’s suspected programs to develop nuclear weapons. A senior U.S. official said in Beijing that North Korea threatened to test, sell or use atomic weapons, depending on Washington’s actions.