Members of the UN Security Council vote unanimously to adopt a resolution imposing sanctions on North Korea on Friday in New York City. The North has vowed to react with 'self-defence measures.' (Osamu Honda/Associated Press)

The United Nations Security Council unanimously passed a resolution Friday that imposes new sanctions on North Korea for its recent missile tests and an underground test of a nuclear device.

The resolution urges countries to reduce financial ties with North Korea, and extends a ban on exports of tanks, artillery and other large arms that represent a significant source of revenue for that country.

All 192 UN member nations are also authorized to inspect cargo vessels at sea or airports if they believe the contents may be used to advance Pyongyang's nuclear or ballistic programs.

South Korean Ambassador Park In-kook, left, and Japanese Ambassador Yukio Takasu speak before Friday's council meeting. (Mary Altaffer/Associated Press)

The U.S. ambassador to the UN, Susan Rice, said it would not be surprising if North Korea reacted to the sanctions with "further provocation."

"There's reason to believe they may respond in an irresponsible fashion to this," she said, adding that she expects the sanctions to have significant impact on North Korea's financing of its weapons programs.

Rice said U.S. officials would seek permission to board and inspect ships believed to be carrying contraband materials to North Korea, but will not try to forcibly board them.

China's UN ambassador, Zhang Yesui, said the resolution demonstrates the international community's "firm opposition" to the nuclear test.

As the same time, he said it also shows the Security Council's determination to resolve the issue "peacefully through dialogue and negotiations" by calling for the resumption of six-party talks aimed at dismantling North Korea's nuclear program.

China urges care in cargo inspections

Zhang cautioned that care should be exercised in carrying out inspections at sea, saying "countries have to act prudently, with sufficient grounds," and that "under no circumstances should there be use or threat of force."

North Korea has been flexing its military muscle in recent months.

On Monday, Pyongyang's main Rodong Sinmun newspaper said the country will consider any sanctions as a declaration of war, and will respond with "due corresponding self-defence measures."

On Tuesday, North Korea said it would use nuclear weapons in a "merciless offensive" if provoked.

North Korean scientists conducted an underground nuclear test on May 24 that drew swift condemnation from the international community. That was the country's second test since 2006.

The Security Council action came a day after a U.S. official said North Korea could be preparing to conduct a third nuclear test.

Won Tae-jae, a South Korean Defence Ministry spokesman, told reporters Friday that another test was "probably possible."

However, South Korea's Yonhap news agency quoted an unidentified intelligence official as saying there was no imminent indication that a test site where the May blast took place was being restored.

With files from The Associated Press