Hill had a meeting with Kim Kye-Gwan on Wednesday morning followed by lunch, a US embassy spokeswoman said.

She gave no details of what the two discussed, but Hill said on Tuesday evening he expected to work out a timeframe for the submission of the declaration, and focus on how to complete phase two of a disarmament agreement.

Phase two refers to the disablement of nuclear facilities in North Korea, as part of a landmark deal reached last year with the United States, China, Japan, Russia and South Korea.

"I think we're going to talk about the issue of how we can complete phase two, what the elements are, putting together this declaration package, and how we might go on from there," he told reporters Tuesday evening.

Hill is due to meet his Japanese counterpart Akitaka Saiki for dinner on Wednesday evening, before briefing reporters on the day's discussions.

Under the six-party deal, North Korea agreed last year to disable nuclear plants at its key Yongbyon facility in exchange for aid and diplomatic recognition.

As part of that deal, Pyongyang was to hand over a full declaration of all its nuclear activities by December 31 last year.

But disputes over the declaration have blocked the start of the final phase of the process -- the permanent dismantling of the plants and the handover of all atomic material.

The biggest sticking points have centred on US suspicions that North Korea had a secret uranium enrichment programme and was involved in building a nuclear reactor in Syria on a site that Israel bombed last September.

North Korea has not admitted to either allegations.

China is the host of the six-party talks, and Chinese envoy Wu Dawei has this week met with Hill and Kim in Beijing, as well as the negotiators from Japan and South Korea.