"There are a number of states that are telling the North Koreans that further escalation would not be in their interests or in the interests of peace and security," she told reporters aboard her official airplane.

Earlier, White House spokesman Tony Snow indicated that Washington fully expected Pyongyang to carry out another nuclear test, saying: "The North Koreans have made no secret of their desire to be provocative."

"It would not be a good thing for them, but it certainly would not be out of character," said Snow.

Asked to elaborate, he noted that the UN Security Council had unanimously adopted sanctions on North Korea after a first test on October 9 and added that if North Korean leaders "believe that somehow people are going to give them a pass on this, they're going to find out that they're wrong."

Snow also shrugged off Pyongyang's announcement, in one of its harshest statements in years, that it viewed UN sanctions imposed after the first test as "a declaration of war" and that it was ready for battle.

"I don't think North Korea has declared war. I think what it did is it tried to characterize the UN resolution as an act of war, which it is not," said the spokesman.

Separately, a US intelligence official said that activity detected at potential North Korean test sites could be consistent with preparations for a second nuclear test but not necessarily evidence a test is imminent.

"How close they may be to pulling the chain or pressing a button is what's not clear," said the official, who spoke on condition of anonymity.

"It is reasonable to expect the government of North Korea will do what it can to test the will, the determination and the unity of the United Nations, the United Nations Security Council, and the other members of the six-party talks," said Snow.

Those negotiations, stalled since November 2005, group China, Japan, South Korea, Russia and the United States in an effort to convince North Korea to give up nuclear weapons in exchange for economic aid and an end to its international isolation.

Rice, seeking to prepare an even tougher response to any second nuclear test, left Washington Tuesday and was scheduled to hold talks with Japanese leaders in Tokyo on Wednesday and then meet together with her Japanese and South Korean counterparts in Seoul on Thursday.

The top US diplomat will then meet Chinese leaders in Beijing before heading to Moscow.

US officials said she was bearing an ambitious plan for inspections of North Korean sea, land and air shipments to ensure the erratic regime does not sell its newly proven nuclear arsenal to terrorists or rogue states.

North Korea walked away from the six-party talks a year ago, after the United States imposed sanctions on an Asian bank alleged to be acting as a clearinghouse for illicit North Korean trade and finance activities.

Rice's top envoy on the Korean issue, Assistant Secretary of State Christopher Hill, warned in Seoul that Washington would regard a second nuclear test as "a very belligerent answer" from North Korea and said the international community would respond "very clearly" to such an action.

Meanwhile, China and Russia, long-time allies of North Korea and the most reluctant of the major powers to impose sanctions on the reclusive state, vowed Tuesday to enforce the UN resolution.

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