The governing board of the UN nuclear watchdog agency has passed a resolution declaring North Korea in breach of UN safeguards and sent the issue to the UN Security Council.
The International Atomic Energy Agency's (IAEA) 35-nation governing board said Pyongyang was in "non-compliance", a diplomatic codeword which brings the issue to the Security Council. The Security Council has the power to take steps against North Korea, including economic sanctions.
Earlier North Korea, eyeing US plans to reinforce its military presence with alarm, said it would regard UN sanctions as tantamount to a declaration of war.
Russia and Cuba abstained from the vote, a diplomat from a board member state said.
"The resolution as drafted was passed and is going on to New York," the diplomat said, referring to the UN Security Council headquarters.
The nuclear crisis on the Korean peninsular erupted last October when Washington said Pyongyang had admitted to pursuing a programme to enrich uranium in violation of a 1994 accord, under which it froze its nuclear programme in exchange for two atomic power reactors and economic assistance.
Since December, Pyongyang has expelled IAEA inspectors, withdrawn from the nuclear Non-Proliferation Treaty (NPT), restarted a mothballed nuclear complex capable of producing weapons-grade plutonium and threatened to resume missile tests.
European Union foreign policy chief Mr Javier Solana, concluding a three-day visit to Seoul, said one option Washington has so far ruled out - direct negotiations with Pyongyang - was central to resolving the standoff.
But Washington has refused negotiations with Pyongyang, saying it must first dismantle its nuclear programs.