South Korea is calling for "flexibility" in the amount and type of information North Korea is due to release about its nuclear programs. Six-nation talks on the North's programs are unlikely to reconvene as expected this month, in an apparent snag over what should be included in the North Korean declaration. As VOA's Kurt Achin reports, a sense of urgency is building among officials in the South Korean capital.

A spokesman for South Korean President Roh Moo-hyun said Thursday that Seoul would like to see six-nation talks aimed at ending North Korea's nuclear capabilities reconvene "as soon as possible."

The talks, involving the two Koreas, China, Russia, Japan and the United States, were widely expected to resume in the Chinese capital this month. The next topic of business for the talks is to review a declaration by Pyongyang of all its nuclear facilities, weapons, and materials - the latest step in a multi-stage agreement aimed at dismantling North Korea's nuclear capabilities altogether.

However, South Korean Foreign Minister Song Min-soon warned Thursday that the talks now run the risk of falling apart. He says the six-nation dialogue "sits at a very critical juncture of stably moving ahead or being crippled."

Song says the dialogue partners were aiming for the end of the year as a deadline for a formal review of the North's nuclear declaration. Now, he says the six parties will have to show "flexibility."

Song was quoted in local media as saying the United States is ready to move ahead in the talks, and the process will move forward as soon as North Korea builds some confidence and "admits what it has done in the past."

U.S. Assistant Secretary of State Christopher Hill, the senior U.S. delegate to the six party talks, says Washington has "very good evidence" North Korea obtained uranium enrichment equipment and technology from Pakistan. Hill says North Korea's declaration must account for Pyongyang's uranium-related activities, which the North has never publicly admitted.

Hill said North Korea must submit at least a draft declaration by the end of the year.

Dan Pinkston, North Asia analyst for the International Crisis Group, says North Korea's apparent reluctance to admit to the uranium-based program may be holding up the declaration.

"I think on the uranium enrichment side there's a lot of explaining to do, and they can't dismiss a lot of the procurement activities in the past," he said.

Hill was in North Korea earlier this week for a visit to the North's main nuclear facility at Yongbyon, which Pyongyang has been disabling as part of the six-nation diplomacy.

Experts say even if the North's nuclear production facilities are dismantled, however, it will be difficult to account for and destroy all of its existing stocks of nuclear materials and weapons.

Apart from the nuclear diplomacy, North-South Korean ties have been moving forward briskly. South Korea's Unification Ministry confirmed Thursday that the South has completed a transfer of 400,000 tons of rice to the impoverished North.

North-South cargo trains are expected to begin rolling next week through the North Korean city of Kaesong, where hundreds of South Koreans also began scheduling package tours this week. High-level inter-Korean talks to advance a wide range of new North-South projects are wrapping up here in Seoul Thursday.