North Korea has invited American experts to visit its top nuclear facility at Yongbyon.
Yongbyon has been off-limits to outsiders for a year
The visit, set to take place next week, will mark the first time outsiders have seen the plant since inspectors were forced to leave a year ago.
A US paper said the team will include a nuclear expert, congressional aides and a former state department member.
The White House has confirmed the invitation, but stressed it was not an official US Government mission.
"It's not our deal," deputy state department spokesman Adam Ereli told journalists at a news briefing in Washington.
Nevertheless, it is clear that the January visit could not go ahead without the blessing of the Bush administration, the BBC's Jon Leyne in Washington says.
A congressional visit to North Korea planned for last October was blocked by the White House, our correspondent says.
This time it appears that President Bush is more open to the prospect of dialogue with Pyongyang, he adds.
North Korea is under pressure from its ally China to resume talks with the US on its nuclear ambitions.
The last round of negotiations, held in Beijing in August, ended without progress.
Site of several nuclear facilities, 100km north of Pyongyang
Includes 5MWt experimental nuclear reactor and fuel rod storage facility
North Korea says it has reprocessed plutonium from 8,000 spent fuel rods at site
The USA Today newspaper said the visitors to Yongbyon would include Sig Hecker, a former director of the US' top nuclear facility, the Los Alamos National Laboratory.
Other delegates were said to include a China expert from Stanford University, two Senate foreign policy aides who have visited the North Korean capital of Pyongyang before, and a former State Department official who has been involved in negotiations with North Korea.
An official at the South Korean Foreign Ministry confirmed the report's detail to the BBC, though it remained unclear which of the various facilities at Yongbyon would be open to the visitors.
The BBC's Seoul correspondent, Charles Scanlon, says that North Korea has threatened on a number of occasions to show off what it calls its nuclear deterrent, and the visit would provide such an opportunity.
North Korea and the US have been locked in a stand-off over the nuclear issue for over a year.
Last year the North claimed to have finished reprocessing 8,000 spent fuel rods being stored at Yongbyon, enough to help it build up to six more nuclear weapons.
Foreign intelligence agencies have been sceptical about the claims, but have been unable to check them.
Some analysts see the North's claims as bargaining counters, as it seeks to negotiate diplomatic recognition and economic aid from the US.
The negotiations have been bogged down over the timing of concessions to be made, but news of the proposed visit suggested some diplomatic progress had been made.
The Bush administration withdrew support for a congressional visit to North Korea in October because it said the timing was not appropriate. The Congressmen had also been promised a tour of Yongbyon.
North Korea said at the weekend that it would take part in fresh diplomatic talks with the US and its allies early this year.