North Korea will not let inspectors from the International Atomic Energy Agency examine its nuclear programme, Japanese media said, citing unnamed diplomatic sources.
Pyongyang said it would reject IAEA inspections after the United States called off promised food aid in the wake of North Korea's failed rocket launch last week, sources said according to the Yomiuri Shimbun.
Under a much-trumpeted agreement reached in February, the US had promised thousands of tonnes of much-needed food aid for the impoverished state.
In exchange, Washington had extracted promises that Pyongyang would suspend enrichment of uranium at its Yongbyon plant and cancel nuclear and missile tests.
That agreement collapsed with Friday's launch of what North Korea insisted was a satellite, but what the US and its allies said was a barely disguised missile test.
Pyongyang's official media had said the hermit state would stick by its side of the bargain even after the rocket disintegrated in mid-air and plunged into the Yellow Sea and was now expected to claim Washington had reneged first, the Japanese paper said.
Abandoning the agreement means North Korea will not feel bound by its terms -- and makes it more likely it will pursue a third nuclear test, the paper cited sources as saying.
UN TOUGHENS SANCTIONS
The UN Security Council ordered tightened sanctions on North Korea over its failed rocket launch and warned of new action if the isolated state stages a nuclear test.
The 15-member council -- including the North's closest ally China and nuclear-armed Pakistan -- "strongly condemned" the launch in a statement which highlighted "grave security concerns" in Asia.
The council ordered new "entities and items" to be added within two weeks to the sanctions committee list created after North Korea staged nuclear tests in 2006 and 2009.
It also ordered the sanctions committee to revise the individuals and North Korean firms subject to asset freezes under the international measures.
North Korea's UN mission made no immediate comment on the Security Council action.
US ambassador Susan Rice, the council president for April, said the sanctions committee would draw up a list of new "proliferation sensitive technology" to be banned for transfer to and from North Korea."
The United States would propose a "robust package of new designations" to the committee, Rice told reporters. This would include the names of companies linked to North Korea's ballistic missile and nuclear programs.
The council said the launch of the rocket, which disintegrated over the Yellow Sea shortly after blast off, was a "serious violation" of UN resolutions 1718 and 1874. The Security Council "strongly condemned" the act.
North Korea said its rocket launch was to put a weather satellite into orbit, but the United States and its allies said it was an attempt to test a missile launcher.
The council demanded that North Korea hold back from new launches "using ballistic missile technology," suspend "all activities related to its ballistic missile program" and keep to its promised "moratorium on missile launches."
"The Security Council expresses its determination to take action accordingly in the event of a further DPRK launch or nuclear test," said the statement.
Japanese and South Korean analysts and officials say satellite imagery showing what preparations at the North Korean town of Punggye-ri -- where nuclear blasts were staged in 2006 and 2009 -- suggest a test could be imminent.
Rice highlighted that it was a "fact of history" that rocket test launches in 2006 and 2009 were soon followed by nuclear tests.
"Clearly the potential for that pattern to persist is one that all members of the international community are mindful of and think would be a disastrous course for the North to pursue," she said.
Rice and other diplomats highlighted the unanimity of the Council's message and speed with which it was agreed.
In 2009, it took weeks for the council to agree a statement on the North's nuclear test, as it did last year when North Korea was accused of sinking a warship of the rival South.
"China has sent a strong message to its close ally by signing up to this statement now and so quickly," one council diplomat told AFP, on condition of anonymity.
Diplomats also stressed Pakistan and India's current presence on the Security Council. Pakistan is sensitive because of its own nuclear bomb, while its nuclear scientist Abdul Qadeer Khan sold nuclear secrets to North Korea.
China has publicly urged restraint over North Korea's missile launch and called for world powers to work to reopen long stalled talks on the North's nuclear weapons -- which involve the two Koreas, the United States, Japan, Russia and China.
The statement made no mention of the six-nation talks, however.
China called for more dialogue following the Security Council action. "It has been proven that dialogue and consultations are the only correct way to solve problems," foreign ministry spokesman Liu Weimin said, according to the state Xinhua news agency.
Japan's Foreign Minister Koichiro Gemba said the UN action was "of great significance for the security of the East Asia region as a whole over which the launch this time has caused grave concerns," Kyodo news agency reported.