"There should be no room for misunderstanding or distortion when we actually begin verification," Japanese nuclear negotiator Akitaka Saiki said after meeting US envoy Christopher Hill and his South Korean counterpart Kim Sook.

The three agreed to try to get Pyongyang to commit on paper to a framework for verifying its nuclear disarmament at six-nation talks that are expected to be held on Monday in Beijing and will also include China and Russia.

The documents should cover the removal of samples from North Korea's nuclear facilities, despite Pyongyang's strong objections, they agreed.

"We will make an effort to complete North Korea's denuclearisation," South Korea's Kim said.

Hill, who is expected to meet North Korean Vice Foreign Minister Kim Kye Gwan in Singapore later this week, said he hoped Pyongyang would realise "that their security lies in having good relations with all of their neighbours, rather than in a unilateral arsenal of their own."

He said the United States, Japan and South Korea were united on the need to improve strained ties in the region.

"The three of us have a very strong and broad understanding of the need to create better relations among states in the region, and I hope the six-party process can take this forward into the future," Hill said.

US Secretary of State Condoleezza Rice has said the heads of the six delegations should aim to finalise a plan allowing for outside verification of the communist North's disarmament.

Hill later said in an interview with Japan's Kyodo News that he did not expect "big changes" in the six-party talks after US president-elect Barack Obama takes office in January.

North Korea tested an atomic weapon in October 2006 before agreeing to return to the six-party negotiations.

The United States struck North Korea off a terror blacklist in October after saying that Pyongyang had agreed to steps to verify disarmament and to resume disabling its atomic plants following a hiatus lasting several months.

However, Pyongyang disputes a US claim that it agreed to the removal of samples, saying external verification of its nuclear inventory would involve only field visits, confirmation of documents and interviews with technicians.

The US State Department has insisted that sampling is part of the deal that Hill reached during a visit to Pyongyang on October 1-3.