BEIJING - Talks aimed at ending North Korea's nuclear threat will focus on Tuesday on how to disable the reactor at the heart of its nuclear program and begin mapping out future disarmament steps, the chief US envoy said.

US Assistant Secretary of State Christopher Hill speaks to the media in Beijing, March 19, 2007. [Reuters]

US Assistant Secretary of State Christopher Hill said the six-party talks in Beijing would consider what happens after a mid-April deadline, when North Korea is due to shut the Yongbyon reactor in return for economic aid and security assurances spelled out in an initial February 13 agreement.

"Clearly we have to meet all the 60-day milestones. That's why we're here - to review that, and we'll be doing that today," he told reporters on Tuesday.

"Frankly, I hope the 60-day discussions will go pretty quickly today and we can get onto the lengthier discussions about the next phase," Hill said.

Tasks for the six parties - the two Koreas, the United States, host China, Japan and Russia - after the deadline would involve "disabling" the reactor and requiring that North Korea report other nuclear activities.

Those steps promise to test the wary North, which exploded its first nuclear device last year.

"We need to know what the full picture of their nuclear programs are, so that when they're abandoned and dismantled we've done all of it," Hill said.

As this session of talks opened on Monday, the United States announced that $25 million in North Korean accounts frozen at Macau's Banco Delta Asia would be released to Pyongyang, overcoming an impasse that had caused North Korea to boycott the six-party negotiators for over a year.  

Washington had accused the Macau bank of harboring illicit North Korean earnings.

North Korea has rejected the charges, and its envoy Kim Kye-gwan has said that his country wanted that money back before it shuts the Yongbyon plant.

Kim has yet to say publicly whether Pyongyang thinks the US announcement was acceptable, but diplomats sounded hopeful.

One diplomatic source said Kim softened "somewhat" when he heard about the US decision on its frozen funds.

And South Korea's Yonhap news agency quoted sources as saying Kim had explicitly confirmed that his country would see through its pledge to shut down nuclear facilities.

The six-party talks scheduled to go through to Wednesday are also likely to discuss the other nuclear activities that North Korea must report.

Most thorny may be Pyongyang's role in highly enriched uranium (HEU) technology, which can be used to make the fissile material in nuclear weapons without running a tell-tale reactor.

North Korea has denied enriching uranium.

US officials have recently steered away from the Bush administration's earlier claims that Pyongyang was close to mastering the complex process. Hill said Pyongyang needed to make a full declaration, including dealings with other countries.

Talks are also hampered by distrust between Pyongyang and other countries at the negotiating table.

The North's official KCNA news agency accused Tokyo of trying to scuttle the talks and said North Korea does not want energy aid from Japan as a part of the deal to end Pyongyang's nuclear weapons program.

Japan has said it will not give full-scale economic aid to North Korea or establish diplomatic ties unless a feud over Japanese citizens kidnapped by Pyongyang in the 1970s and 1980s to train its spies has been resolved.