North Korea said Monday a 1992 agreement with South Korea to keep the Korean Peninsula free of nuclear weapons was nullified, citing a "sinister" U.S. agenda.

"The joint agreement to keep the Korean Peninsula (search) nuclear free was nullified because of a sinister and hostile U.S. policy against North Korea," the North's official news agency KCNA said. The statement was monitored by South Korean news agency Yonhap.

The two Koreas signed the agreement in January 1992 pledging to renounce hostilities and ban the development and deployment of nuclear weapons on the divided peninsula.

It was the last remaining legal obligation under which North Korea was banned from developing atomic arms. Last January, North Korea withdrew from the Nuclear Nonproliferation Treaty (search), a global accord to prevent a spread of nuclear weapons.

Monday's announcement came as South Korean President Roh Moo-hyun (search) was visiting the United States for a summit with President Bush on North Korea's nuclear ambitions.

During nuclear talks in Beijing last month, U.S. officials said North Korea claimed it had reprocessed 8,000 spent nuclear fuel rods -- a move that could yield several atomic bombs within months.

The talks were the first since the crisis flared in October, when Washington said North Korea admitted running a secret nuclear weapons program in violation of a 1994 treaty.