SEOUL: A US envoy is set Wednesday to pursue efforts to bring North Korea back to stalled six-nation nuclear disarmament negotiations, but experts said Pyongyang has a different agenda for the rare top-level visit.

Stephen Bosworth arrived in the communist state Tuesday for the first official meeting between the two countries since US President Barack Obama took office in January pledging direct diplomacy.

The US State Department said Bosworth and his six-strong team were likely to have held talks Tuesday but that their "primary meetings" would be on Wednesday.

Washington says Bosworth's aim is to persuade the North to return to the six-party talks and to reaffirm a 2005 accord offering aid, diplomatic benefits and talks on a formal peace treaty in return for full denuclearisation.

But after a turbulent year which saw the North quit the six-party forum and stage a second atomic weapons test, experts say the regime now has a new agenda.

Pyongyang has long sought direct talks with Washington in preference to the six-party talks which were launched in 2003 and also group South Korea, Japan, Russia and China.

It says it needs its nuclear arsenal in the face of US "hostility" and maintains that a peace deal with Washington formally ending the 1950-53 war is key to resolving the nuclear standoff.

Charles Pritchard, a former US negotiator with Pyongyang who visited the North last month said Tuesday he doubted that Bosworth's meetings would yield a breakthrough.

Pritchard said a North Korean official "on a number of occasions and in a number of ways told us if Ambassador Bosworth were to come and simply and suddenly say, 'return to six-party talks', that that in fact would be a waste of time."

Pritchard told a Washington news conference that the official, Ri Gun -- director general of North American affairs at the foreign ministry -- instead sought talks on a peace treaty between the North and the United States.

The war in which a US-led UN command fought for the South ended only in an armistice, which Pyongyang has in any case disavowed.

Ri said North Korea needed a treaty to end the "inconsistency" in US policy between different administrations, Pritchard said.

"I think this is a negotiating ploy to avoid the discussion and commitment to come to six-party talks," added Pritchard, who now heads the Korea Economic Institute.

Scott Snyder, director of the Centre for US-North Korea Policy at the Asia Foundation, took the same trip as Pritchard.

He said he forecasts a "difficult conversation" this week because the North wants to be treated as a nuclear power after its second test -- something which Washington insists will never happen.

"Essentially, Pyongyang's new offer -- as a 'nuclear weapons state' -- has shifted from the denuclearisation for normalisation deal at the core of the 2005 Six Party Joint Statement to 'Peace first; denuclearisation, maybe later'," Snyder wrote in the centre's newsletter.

State Department spokesman Philip Crowley said he does not expect to hear from Bosworth's team until its scheduled return to Seoul Thursday. He noted that the United States was not the only party to a peace treaty, which would have to be discussed in a multilateral context.

Stung by international censure of its long-range rocket launch, the North in April declared the six-party talks "dead".

It staged its second nuclear test the following month and followed up with a series of missile launches, attracting tougher UN sanctions.

In August, as former president Bill Clinton visited Pyongyang to secure the release of two US journalists, the North began striking a softer note.

In October it announced it is ready to return to the six-nation talks, but only if direct discussions with the United States prove satisfactory.