GENEVA/SEOUL -- North Korean and U.S. diplomats on Tuesday began a second day of talks during which Washington wants to see whether the North is indeed prepared to take concrete steps toward denuclearization before the stalled six-nation talks can resume.

North Korean Vice Foreign Minister Kim Kye-gwan and Stephen Bosworth, Washington's outgoing top envoy for Pyongyang, and his successor Glyn Davies sat down at the North's U.N. mission in Geneva for the discussions, the second bilateral encounter between both sides in less than three months.

After Monday's "very intense discussions," Bosworth told reporters both sides "narrowed some differences but we still have differences that we have to resolve." The North's delegation did not comment.

South Korea and the U.S. have laid out a series of "pre-steps" before resuming the multilateral forum, which also involves China, Russia and Japan. The broader talks have been at a standstill since April 2009 when the North quit the negotiating table, then conducted its second nuclear test a month later.

Among other preconditions, Seoul and Washington have insisted that Pyongyang suspend its uranium enrichment program and allow international inspectors to verify the suspension ahead of the aid-for-disarmament talks.

Other conditions include a monitored shutdown of all activities at the North's nuclear complex in Yongbyon, a nuclear and missile test moratorium and a pledge not to attack South Korea again.

Last year, North Korea launched two military attacks on the South, killing a total of 50 South Koreans, mostly military.

Still, prospects for the Geneva talks appeared dim as North Korean leader Kim Jong-il has repeated in recent days that Pyongyang is ready to return to the six-party talks "without any preconditions."

North Korea has also refused to discuss its uranium enrichment program, arguing it is enriching uranium for peaceful purposes.

Adding new urgency to resuming the six-party talks, North Korea revealed in November last year that it was running an industrial-scale uranium enrichment facility. Highly enriched uranium can be used to make weapons, providing Pyongyang with a second way of building nuclear bombs in addition to its existing plutonium program.

Hours before the second day of talks began, South Korea insisted again that the North must agree to stop enriching uranium.

"The most essential pre-step is a freeze and international inspection of the uranium enrichment facility," a senior Seoul official said on the condition of anonymity. "North Korea must answer for the issue during the Geneva talks."

Unless North Korea agrees to stop enriching uranium during the Geneva talks, the official said, there will be no meaningful progress. (Yonhap News)