The United States on Thursday for the first time admitted it was scaling back its demands of North Korea in a bid to break a diplomatic stalemate on dismantling Pyongyang's nuclear arms programs.

The top Asia hand at the US National Security Council, Dennis Wilder, said North Korea was not "off the hook" on fully declaring its atomic programs, but that proliferation issues would be "handled in a different manner."

And US Secretary of State Condoleezza Rice indicated the overdue declaration -- agreed as part of a landmark February 2007 deal grouping China, Japan, North and South Korea, Russia and the United States -- might not be made public.

"Have we made progress through the six-party framework? Yes. Is there still reason for caution and skepticism? Yes," Rice told reporters.

In a seeming concession to the North Koreans, she hinted the document could be kept private, allowing Pyongyang to save face.

"There will be, undoubtedly, briefings for Congress," on any final arrangement, she said, warning: "This is a diplomatic matter and not everything in diplomacy is public."

For months, Washington had demanded that Pyongyang detail all of its nuclear activities, including any proliferation of nuclear know-how, in a declaration North Korea had agreed to provide by December 31, 2007.

Under the agreement, Pyongyang has begun disabling its key atomic plant in return for energy aid and major diplomatic and security benefits that could eventually mean removal from the US list of state sponsors of terrorism.

The US government is eager to see the denuclearization drive completed before President George W. Bush leaves office in January 2009. The North tested a nuclear bomb in October 2006.

On Wednesday, the United States said it was working with its diplomatic partners on a a new mechanism to scrutinize any nuclear declaration by North Korea.

The announcement of the new verification measure came amid criticism of a reported prospective deal reached earlier this month between US and North Korean envoys, which caused a great deal of skepticism among experts.

They accused Washington of back-tracking on the terms of the original accord.

But Rice has denied the existence of such a deal, and insisted Thursday: "The outcome we and our partners require is a full accounting from North Korea of all its nuclear programs, including any uranium and nuclear proliferation activities.

"I want to emphasize that we are at the beginnning of a very complex process, not the end, a process that must lead to the actual removal, for the first time in history, of nuclear material from North Korea and verifiable end to its nuclear programs."

Earlier Thursday, South Korea's new chief nuclear negotiator Kim Sook said the disarmament talks with Pyongyang were "reaching a critical stage."

"We are pushing to resume the six-party talks as soon as the declaration is submitted. All participatory countries agree to this idea," Kim told a briefing.

Asked about a news report that said US diplomats plan to visit Pyongyang to get the talks moving, Kim said: "It will be for the United States and North Korea to hold working-level discussions aimed at working out a declaration, which will be a main topic for the next round of six-party talks."

Washington says the document should clear up suspicions about an alleged secret uranium enrichment program and suspected proliferation to Syria. North Korea denies both charges.

Hopes of breaking the impasse have emerged since last week when top US nuclear envoy Christopher Hill and his North Korean counterpart Kim Kye-Gwan met in Singapore to debate the form of the declaration.

"All six parties have an obligation as well which we agreed to undertake in parallel with North Korea's submission of a declaration, a declaration that we will verify vigorously," Rice added.

If North Korea provides the nuclear declaration, the parties could move to implement the final phase of dismantling its nuclear program and materials.