In a resolution adopted by consensus, the general conference of the International Atomic Energy Agency urged North Korea to "completely dismantle" its nuclear arms efforts. It also called on the communist regime to "accept comprehensive IAEA safeguards and cooperate with the agency in their full and effective implementation."
North Korea severed its ties with the agency last year and the conference has no way to enforce the resolution.
Still, the consensus document reflected international concern over North Korea's declared intention to build nuclear weapons.
IAEA Director-General Mohamed ElBaradei told the agency's board last week that the nuclear standoff with North Korea poses a "serious and immediate challenge" to the global effort to control the spread of atomic weaponry.
ElBaradei said the North's nuclear ambitions will remain unclear until the regime allows IAEA inspectors to return.
The crisis began in October, when U.S. officials said North Korea admitted having a nuclear weapons program in violation of a 1994 agreement. The IAEA then declared North Korea in violation of the Nuclear Nonproliferation Treaty in February.
The United States and its allies suspended oil shipments to the isolated communist country. North Korea in turn expelled IAEA inspectors, disabled the agency's monitoring cameras, withdrew from the global nuclear arms-control treaty and said it would reactivate its main nuclear complex, frozen since 1994.
The CIA estimates that North Korea has one or two nuclear weapons.
But some American intelligence analysts are becoming increasingly concerned that North Korea may have three, four or even six nuclear weapons, U.S. officials said.
Each new weapon would enhance North Korea's nuclear capability and give it significantly more authority at the negotiating table — or even allow its leaders to sell a weapon on the black market, officials and experts warn.
China, North Korea's last remaining major ally, hosted six-nation talks last month on North Korea's nuclear program. The other participants were the United States, Russia, South Korea and Japan.
China is trying to arrange a new round of negotiations after last month's meeting ended without an agreement on how to ease tensions.
U.S. Deputy Assistant Secretary of State Andrew K. Semmel told the conference Wednesday that North Korea's nuclear threat is "a challenge that is unprecedented in the history of the nuclear nonproliferation regime." He criticized the regime for its "defiant and provocative statements and threats."