'No surprises'

Christopher Hill, the US nuclear envoy who arrived in the South Korean capital of Seoul for consultations before the talks, said he expects the meeting to be difficult.

"We did have a discussion about the need for [North Korea] to do more to meet Japanese concerns, especially on the abduction matter," he said.

"We need a situation where, when we begin the verification, there are no surprises."

Though it agreed to disarm, North Korea still denies ever saying it would allow inspectors to take samples from its nuclear complex, a key process to verify its accounting of past nuclear activities.

Yu Myung Hwan, South Korea's foreign minister, said earlier this week that the nations will press North Korea to agree in writing a protocol for checking the extent of its nuclear programme.

The forum will also discuss a timetable for completing the delivery of heavy fuel oil to North Korea, Yu said.

'Security concerns'

The six-party talks aim to find a peaceful resolution toward worldwide security concerns, however, they have stalled over how to verify North Korea's nuclear holdings.

North Korea admitted in 2002 that it possessed nuclear weapons, prompting international disarmament talks after North Korea withdrew from the Nuclear Non-Proliferation treaty the following year.

Five rounds of talks from 2003 to 2007 had produced little net progress, until North Korea agreed to shut down its nuclear facilities in 2007.

In return, North Korea would normalise diplomatic relations with the US and receive energy aid.

However, North Korea has been at odds with Japan for not providing its share of the one million metric tonnes of heavy fuel oil pledged under the disarmament accords.

Japan-North Korea relations

Japan has refused to join the four other countries, China, Russia, South Korea and the US in providing aid until North Korea accounts for the kidnapping of Japanese nationals during the Cold War era.

North Korea acknowledged having kidnapped 13 Japanese citizens in 2002, allowing five people to return home and said the remaining eight had died.

Japan, however, has demanded proof of the deaths and an inquiry into additional suspected kidnapping cases, an emotional issue that has slowed progress in the nuclear disarmament talks.

The North Korean foreign ministry has issued several statements in the past. In the most recent it complained that Japan "persistently and impertinently insists on its participation in the talks though it is refusing to fulfil its commitment".

Tokyo's aim is to block denuclearisation to give it a pretext to boost its military power, the statement said. 

"Such a country has neither justification nor qualification to participate in the talks," it said, noting that other countries are wiling to provide Japan's share of aid.

The two countries struck a breakthrough deal in June under which North Korea pledged to finally resolve the abductions of Japanese citizens, but no major progress has been made since then.