Secretary of State Colin Powell says the United States will continue working for a diplomatic resolution of the problem of North Korea's nuclear program, despite the latest suggestion by Pyongyang that it is building weapons from spent reactor fuel.

Mr. Powell says the United States has no evidence to confirm North Korea's claim that it is using fissile material from reactor fuel rods to make weapons, and he says that in any case the Bush administration will continue to pursue multi-party talks to try to resolve the issue.

In a session with foreign reporters in Washington, the secretary said Thursday's statement from Pyongyang was the third time North Korea had claimed to have finished reprocessing spent fuel rods from the reactor complex it reopened last year.

"The North Koreans go out of their way to make these statements from time to time," he said. "And we will continue to pursue diplomacy and not react to each and every one of their statements, which seems to be a repeat of the previous statement.'

The secretary of state added that North Korea's claims should be a matter of "the most serious concern" to the international community, and said the United States is looking to countries in the region to press North Korea to return to multilateral talks on the issue hosted by China.

The last meeting in late August, which also included South Korea, Japan and Russia, ended inconclusively. But Mr. Powell said the United States is looking for a way that North Korea can be given the security guarantees it says it needs to give up its nuclear weapons ambitions.

"The United States is reviewing the results of the six-party meeting that we held in Beijing not too long ago, and we are examining ways, in cooperation with our colleagues in the area, to provide the kinds of security assurances that might help move the process further along," he said.

The United States has ruled out a North Korean demand for a formal non-aggression treaty, but officials have said there should be ways to formalize repeated verbal assurances by the Bush administration that it has no intention of attacking that country.