"This is an interesting step on their part, a positive step, and we hope that it will allow us to move more rapidly to six-party framework talks," Powell told reporters.

"I am encouraged, I am encouraged by the statement the North Koreans made," he said.

North Korea offered earlier to refrain from testing and producing nuclear weapons in what it said was a "bold concession" to the United States.

The offer came as two unofficial US delegations arrived in Pyongyang hoping for a tour of the Yongbyon nuclear complex at the center of a crisis which erupted in October 2002, when Washington accused North Korea of breaching an anti-nuclear pact.

After several days of pessimistic noises from Russia and South Korea over the delay in convening new six-nation talks on the crisis, Powell injected a more hopeful tone.

"Because we're not sitting at a table, does not mean we have not been talking to each other, and a lot of papers have gone back and forth," he said.

"We are in touch with our four partners in this effort and some of our partners are directly in touch with North Korea. So we've been doing a lot.

The dialogue, which ended inconclusively after a first session in August had been pencilled in for December, but according to Japanese and South Korean officials could now slip back to next month at the earliest.

The White House was noticably less upbeat than Powell on North Korea's statement.

"I think it would be positive for North Korea to return to those six-party talks, so we can discuss how they go about ending their nuclear weapons program," said spokesman Scott McClellan.

Some observers believe that Powell's State Department is much keener to enter dialogue with North Korea than elements of the White House and Pentagon political establishment.

Bush administration officials insist they are on the same page on North Korea policy.

The United States has demanded an irrevocable and verifiable decision by North Korea to abandon its quest for nuclear weapons.

On Monday it warned the Stalinist state that it could expect no rewards from Washington just for showing up at talks, also involving China, Russia, South Korea and Japan.

One potential stumbling block is that North Korea's offer included a condition that Washington would deliver "simultaneous" actions including removing North Korea from a State Department list of countries accused of sponsoring terrorism, lifting sanctions and resuming energy aid.

Washington has rejected North Korea's plan for "simultaneous" measures and maintains that it is only willing to discuss "sequencing" of steps to aid Pyongyang at the six-nation talks, not before them.

South Korean government officials said the latest proposal from Pyongyang appeared to contain nothing new but signalled North Korea's desire for dialogue.

Another signal from North Korea came as members of an unofficial US delegation arrived in Pyongyang at the invitation of the Stalinist state.

The team included a former US official who dealt with North Korea policy, a scientist and a top academic.

Another delegation, comprised of two aides to senior senators also arrived in Pyongyang.

The US government has distanced itself from both teams.

WAR.WIRE