SEOUL, South Korea – North Korea boasted publicly for the first time yesterday that it has nuclear weapons and said it will stay away from disarmament talks, dramatically raising the stakes in the 2-year-old dispute. The Bush administration called on Pyongyang to give up its atomic aspirations so life can be better for its impoverished people.

North Korea’s harshly worded pronouncement posed a grave challenge to President Bush, who started his second term with a vow to end North Korea’s nuclear program through six-nation disarmament talks.

“We … have manufactured nukes for self-defense to cope with the Bush administration’s ever-more undisguised policy to isolate and stifle the [North],” the North Korean Foreign Ministry said in a statement carried by the state-run Korean Central News Agency. The agency’s report used the word “nukes” in its English-language dispatch.

Previously, American negotiators said North Korean officials claimed in private talks that they had nuclear weapons and might test one. The North’s U.N. envoy also said last year the country had “weaponized” plutonium from its pool of 8,000 nuclear spent fuel rods.

But yesterday’s statement was the first claim directly from North Korea’s state press that it has a nuclear weapon, confirming the widely held beliefs of international experts that the country has one or two atomic bombs. North Korea is not known to have performed any nuclear tests, and it kicked out U.N. inspectors in 2002, so there is no way to verify its claims.

America and South Korea, the North’s main rivals, played down the revelation and urged the North to return to the six-nation talks that began in 2003 and also include China, Japan, and Russia. Analysts suggested the move by North Korea may be a negotiating tactic aimed at getting more compensation in exchange for giving up its nuclear weapons program.

Secretary of State Rice said North Korea should return to negotiations.

“The world has given them a way out, and we hope they will take that way out,” she said, wrapping up a trip to Europe. “The North Koreans have been told by the president of the United States that the United States has no intention of attacking or invading North Korea.

“The message is clear: Give up these aspirations for nuclear weapons and you know life can be different,” Ms. Rice said, adding that it was the same message Libya understood in renouncing its nuclear ambitions.

In a clear overture to North Korea to help foster the nuclear talks, Mr. Bush refrained from direct criticism of the country in last week’s State of the Union address. He mentioned North Korea only in a single sentence, saying Washington was “working closely with governments in Asia to convince North Korea to abandon its nuclear ambitions.”

Mr. Bush previously branded the North part of an “axis of evil” along with Iran and Saddam Hussein’s Iraq.

Still, Pyongyang yesterday seized on comments by Ms. Rice last month in which she labeled North Korea as one of the “outposts of tyranny” in the world.

“The U.S. disclosed its attempt to topple the political system in [North Korea] at any cost, threatening it with a nuclear stick,” North Korea’s Foreign Ministry said. “This compels us to take a measure to bolster its nuclear weapons arsenal in order to protect the ideology, system, freedom, and democracy chosen by the people in [North Korea].”

The statement said the Bush administration was trying to “mislead” the world in calling for resuming the six party talks while also seeking “regime change” in North Korea.

“This is nothing but a far-fetched logic of gangsters as it is a good example fully revealing the wicked nature and brazen-faced double-dealing tactics of the U.S. as a master hand at plot-breeding and deception,” the statement said.

South Korea urged its neighbor to rejoin the talks, and said it maintains its previously stated estimate that North Korea has enough plutonium to build one or two nuclear bombs.

“We once again urge North Korea to rejoin the six-party talks without conditions so that it can discuss whatever differences it has with the United States and other participants,” said South Korean Foreign Ministry spokesman Lee Kyu-hyung.

Both Ms. Rice and White House spokesman Scott McClellan played down any significance of North Korea’s announcement that it has nuclear weapons, saying it was “rhetoric” that has been heard before.

“We remain committed to a peaceful diplomatic resolution to the nuclear issue with regards to North Korea,” Mr. McClellan said aboard Air Force One en route to North Carolina. “It’s time to talk about how to move forward.”

Washington now must rely on its allies with more direct influence over the North – China and South Korea – to entice North Korea to negotiate.

“The question now is whether Washington is able to persuade and cajole Seoul and Beijing to bribe and pressure North Korea to resume the six-party talks,” said Gary Samore of the London-based International Institute for Strategic Studies. “The U.S. has absolutely no influence, except through other countries.”

Last week, Michael Green, the U.S. National Security Council’s senior director for Asian affairs, traveled to the region to relay Mr. Bush’s desire to restart the diplomatic process to the leaders of China, South Korea, and Japan.

North Korea did leave an opening to return to the table, saying it would stay away until “we have recognized that there is justification for us to attend the talks and there are ample conditions and atmosphere to expect positive results.” North Korea’s economy has been ravaged by famine and natural disasters, and it relies on outside aid to feed its people.