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, in an apparent concession to Pyongyang, indicated the entire overdue declaration might not be made public.

In another turnaround, she hinted that US sanctions against North Korea could be removed even before the hardline communist state's nuclear programs or proliferations activities were verified independently.

"Verification can take some time," she told reporters.

North Korea has been pushing the United States to remove it from the blacklist of state sponsors of terrorism.

Rice said the document incorporating North Korea's proliferation activities 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."

A State Department official, speaking on condition of anonymity, said later that the document would be published "in some form."

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

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

The declaration was part of a February 2007 landmark deal grouping China, Japan, North and South Korea, Russia and the United States.

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

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 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."

Wilder confirmed the United States had had "side negotiations" on the proliferation issue with North Korea and was sending an experts group back to Pyongyang next week "to see if we can make progress on the declaration."

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.

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.

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

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