UNITED NATIONS — The U.N. Security Council voted unanimously on Saturday to impose punishing sanctions on North Korea including ship searches for banned weapons, calling Pyongyang's claimed nuclear test "a clear threat to international peace and security."

North Korea immediately rejected the resolution, and its U.N. ambassador walked out of the council chamber after accusing its members of a "gangster-like" action which neglects the nuclear threat posed by the United States.

The U.S.-sponsored resolution demands that the reclusive communist nation abandon its nuclear weapons program, and orders all countries to prevent North Korea from importing or exporting any material for weapons of mass destruction or ballistic missiles. It orders nations to freeze assets of people or businesses connected to these programs, and ban the individuals from traveling.

The resolution also calls on all countries to inspect cargo leaving and arriving in North Korea to prevent any illegal trafficking in unconventional weapons or ballistic missiles. The final draft was softened from language authorizing searches, but was still unacceptable to China — the North's closest ally — which said it would not carry out any searches.

U.S. Ambassador John Bolton said North Korea's proclaimed test "poses one of the gravest threats to international peace and security that this council has ever had to confront."

"Today, we are sending a strong and clear message to North Korea and other would be proliferators that there will be serious repercussions in continuing to pursue weapons of mass destruction," he said, in what appeared to be a clear warning to Iran whose nuclear ambitions come before the Security Council again next week.

North Korea's U.N. Ambassador Pak Gil Yon countered by blaming the United States for forcing the country to conduct a test because of its "nuclear threat, sanctions and pressure."

"The Democratic People's Republic of Korea is ready for talks, dialogue and confrontation," Ambassador Pak Gil Yon said. "If the United States increases pressure upon the Democratic People's Republic of Korea persistently, the DPRK will continue to take physical countermeasures considering it as a declaration of war."

North Korea has made similar threats in the past, and has also said it might conduct a second nuclear test in response to U.N. sanctions.

The vote came after the United States, Britain and France overcame last-minute differences with Russia and China during what the Russian ambassador called "tense negotiations."