North Korea has ordered UN inspectors to leave, after saying it would quit international nuclear disarmament talks and restart a plant that makes bomb-grade plutonium.
The United Nations' nuclear watchdog, the International Atomic Energy Agency, said North Korea announced it was immediately ceasing cooperation and ordered UN inspectors to leave the country.
North Korea was angered by the UN Security Council condemnation of the country's rocket launch on 5 April as contravening a UN ban. The launch was widely seen as a disguised test of a long-range missile but North Korea said it was for peaceful purposes.
North Korea began taking apart its Soviet-era Yongbyon nuclear plant more than a year ago as a part of a disarmament-for-aid deal it reached with China, Japan, Russia, South Korea and the United States.
US Secretary of State Hillary Clinton strongly criticized the expulsion of the nuclear inspectors and said she hoped the United States and its allies could discuss it with the North.
"We are viewing this as an unnecessary response to the legitimate statement put out of concern by the Security Council," Mrs Clinton told reporters in Washington.