Sputtering talks on ending North Korea's nuclear plans will gain a higher profile this week with an unprecedented meeting of ministers, but lingering questions on the North's ambitions threaten to drag the process down.

U.S. Secretary of State Condoleezza Rice will have her first meeting with the North's top diplomat, Pak Ui-chun, when foreign ministers from six countries involved in North Korean disarmament talks hold discussions at a forum in Singapore tentatively set for Wednesday.

The meeting will add momentum to a disarmament-for-aid deal the North struck with China, Japan, Russia, South Korea and the United States, analysts said, but the informal gathering will likely shine little light on the North's secret plans to enrich uranium for weapons or proliferate technology for profit.

Rice told reporters before a refuelling stop in Ireland on Monday that she would make clear in her first meeting with North Korea this week it must meet its obligations and come clean on all aspects of its nuclear program.

"I believe there will be a very strong message that the obligations need to be met and that the verification protocol really needs to be completed and that it has to be a verification protocol that can give us confidence that we are able to verify the accuracy of the North Korean declaration," Rice said.

In recent weeks, the United States and North Korea have pushed the deal forward, with Pyongyang providing a long-delayed list of its plutonium inventory and Washington starting to take the North off a terrorism blacklist and removing trade sanctions.

"The unanswered issues would be handed over to the next president of the United States," said Kim Sung-han, Korea University international relations professor.

The North's nuclear list did not mention weaponry or facilities other than its well-known Yongbyon nuclear plant where it has been producing weapons-grade plutonium for years.

"The Bush administration is just aiming at disabling the plutonium program completely," Kim said, adding the Bush team did not have enough time to accomplish much more.

Some analysts said the U.S. administration, mindful of its legacy in the last months of the Bush presidency, is paying attention to bipartisan and global pressure to engage North Korea, as well as Iran, at a high level.

The North Korean nuclear talks have a history of taking one step forward and then one step back, and while the administration is hoping to score points, Pyongyang could slow things down by not allowing for verification of its plutonium claims.

Conservative stalwarts have also been criticizing the Bush administration for giving away too much to the North.

But it has been increasingly in North Korea's interest to win concessions from the United States, as the impoverished North has moved away from major benefactor South Korea in anger at the policies of its new president, who has backed a tough line toward Pyongyang.

Once the United States lifts its economic sanctions, analysts estimate North Korea could see a $2 billion (1 billion pounds) boost to its some $20 billion a year economy as it becomes easier for investors to move money in and out of the isolated country.

The Association of South East Asian Nations Regional Forum, held this week in Singapore, is the only annual event that brings together the foreign ministers of the six countries in the nuclear talks.

At a previous meeting in 2004, former U.S. Secretary of State Colin Powell met then North Korean Foreign Minister Paek Nam-sun.