The top U.S nuclear negotiator was meeting his North Korean counterpart in Singapore on Tuesday with hopes of reviving stalled disarmament talks.

U.S. Assistant Secretary of State Christopher Hill said he was unsure of progress in the meeting with North Korea's Kim Kye-gwan, and urged a return to six-nation talks that have been held up by the isolated state's overdue declaration on its nuclear activities.

"I don't think we will have any agreement, we are not looking for an agreement, we are looking to have a consultation on some of the issues that have kept us apart," he told reporters before the meeting.

"They know exactly what the issues are and that we don't want to meet them unless we could achieve something."

The meeting comes at a time of heightened tension on the heavily armed Korean peninsula in recent days after the North's missile tests and threat to attack the South.

Washington wants Pyongyang to deliver a declaration giving a complete accounting of its nuclear programmes as called for in a landmark deal struck in six-party talks between China, Japan, Russia, the two Koreas and the United States in February 2007.

The declaration was due by the end of 2007, and was meant to answer U.S. suspicions of a secret programme to enrich uranium for weapons and proliferating nuclear technology.

North Korea has said it had already made the declaration and the U.S. suspicions were "fictions".

NUCLEAR HURDLE

Gavan McCormack, an East Asia expert at the Australian National University, said that the nuclear declaration was a hurdle that must be crossed in order for the six-party talks to regain momentum.

Diplomatic sources in Tokyo told Reuters the United States and North Korea have been discussing a possible face-saving compromise under which Pyongyang would acknowledge the U.S. assertions in a document separate from its declaration.

"The proposal is face-saving to both sides," one source said. "It is particularly face-saving to North Korea because they don't have to directly admit that they had done something wrong."

Last month, a senior U.S. official said Washington had begun exploring whether Pyongyang might disclose any proliferation and uranium enrichment in a separate document.

If the North makes the declaration, it stands to be removed from a U.S. terrorism blacklist and be better able to tap into finance that could boost its economy.

Hill, who last met Kim about a month ago in Geneva, will fly to Beijing early on Wednesday to meet South Korean, Japanese and Russian officials to brief them on the North Korean situation.