WASHINGTON - In a display of pressure on North Korea, the international nuclear watchdog agency demanded yesterday that the Communist regime reverse its recent moves to develop atomic weapons or face possible punitive action by the United Nations.

Drawing on a consensus of its 35 member countries, the International Atomic Energy Agency's governing board in Vienna, Austria, called on Pyongyang "urgently" to resume cooperating with agency monitors and quickly give up "any nuclear weapons program."

The move means the board is giving North Korea "one more chance to come into compliance" before the U.N. Security Council gets involved, said IAEA Director Mohamed ElBaradei.

The Security Council could impose sanctions or other forms of pressure. Neither the United States nor any other country has raised the possibility of military action. Yesterday, President Bush stressed anew that he seeks a diplomatic solution.

The IAEA action represented the strongest international statement against North Korea since Pyongyang broke out of a series of nonproliferation restraints late last year - first by defiantly confirming a program to develop weapons fuel, and then by shutting down monitoring devices, expelling IAEA inspectors and announcing that it planned to resume operating a nuclear reactor that could create fuel for nuclear weapons.

At the same time, the IAEA allowed North Korea a unspecified number of weeks to change course and also gave the United States more time to overcome differences with Asian powers, including South Korea, Japan, China and Russia, on a strategy to persuade Pyongyang to relent.

While exerting pressure, the IAEA made clear yesterday that there was another path - of dialogue, economic assistance and greater security - open to North Korea.

Saying the international community would not "negotiate under blackmail or under threat," ElBaradei said that once the North Koreans comply with the demands of the international community, "then there is a light at the end of the tunnel for them." Many countries are ready help meet North Korea's economic and security needs, he said.

Yesterday's meeting of the IAEA board in Vienna coincided with the start of two days of meetings in Washington between U.S. officials and envoys from South Korea and Japan, the two countries most directly threatened militarily by North Korea.

Bush, speaking to reporters at the White House, went part way toward meeting South Korea's demand for a U.S. pledge not to attack North Korea, saying, "I went to Korea and clearly said that the United States has no intention of invading North Korea."

He added: "And I'll repeat that: We have no intention of invading North Korea."

The White House welcomed the IAEA step as "appropriate," hailing approval of its resolution by all 35 members.

"What's happening here is you see the world coming together," said White House spokesman Ari Fleischer. "It's not only China, Russia, South Korea, Japan and the United States that are troubled by North Korea's unilateralist actions. The nations that made up the board that voted in Vienna today include Australia, Malaysia, Iran, Cuba. It takes a lot of work to get condemned by Iran and Cuba, and North Korea has done it."

The IAEA board, in its resolution, called on North Korea to cooperate "urgently and fully with the agency by allowing the re-establishment of the required containment and surveillance measures at its nuclear facilities and ... the return of IAEA inspectors."

The resolution said that unless North Korea "takes all necessary steps" to allow the agency to resume monitoring its nuclear facilities, Pyongyang will be in "further noncompliance" with its obligations to the IAEA.

The IAEA is the same agency that, together with the U.N. Monitoring, Verification and Inspection Commission, is searching for weapons of mass destruction in Iraq.

Unlike the Iraq crisis, where the United States has used the threat of going to war on its own to galvanize other countries into pressuring Baghdad, the Bush administration has been deliberately low-key in response to North Korean defiance. A senior U.S. official in Vienna, Kenneth C. Brill, stressed yesterday that the United States "will be patient in those efforts, and we will work closely with other interested states to find a peaceful way forward."

The Bush administration has taken this stance even though North Korea is already believed to possess enough plutonium for two nuclear weapons, possibly even the bombs themselves, and that, with no restraints on its actions, Pyongyang could develop fuel for another half-dozen weapons in a matter of months. Iraq is not yet suspected of having enough fuel to develop a nuclear bomb.

Apart from its preoccupation with Iraq, the Bush administration clearly wants to avoid a war on the Korean Peninsula that analysts say could claim tens of thousands or even hundreds of thousands of lives. About 37,000 U.S. troops are stationed near the demilitarized zone separating the two heavily armed Korean neighbors.

U.S. policy toward North Korea is complicated by South Korea's determination to continue its own steps toward strengthening diplomatic and economic ties with the North in a bid to reduce the constant state of tension on the peninsula.

South Korea has advocated a trade-off in which North Korea would accept renewed restraints on its nuclear program in return for a U.S. pledge not to attack the North.

The United States has refused to be drawn into any negotiations with North Korea or to make any promises as long as Pyongyang continues its defiant posture, but officials have not rejected the South Korean proposal out of hand.

One U.S. official recalled yesterday that that before the exposure last year of a new North Korean program to enrich uranium, suitable for nuclear weapons, the United States had been prepared to present a "bold initiative" for improving relations with North Korea. He indicated that, depending on Pyongyang's actions, that same initiative could be revived.