BEIJING (AFP) - The next stage in ending North Korea's nuclear activities may take months, the chief US envoy on the issue cautioned here on Wednesday ahead of a fresh round of six-nation disarmament talks.

The talks, to start on Thursday, have not been held for nine months amid delays in securing from the reclusive regime a declaration of all its nuclear activities, as agreed in a landmark six-nation accord reached last year.

But the North, which conducted an atomic test in 2006, last month finally delivered the declaration, clearing the way for progress in the negotiations between China, the United States, Russia, the two Koreas and Japan.

After meeting with his North Korean counterpart on Wednesday, US envoy Christopher Hill said he expected the talks to focus on how to verify the North's declaration, including working out site visits and interviews.

"I think there is an understanding that we have to move forward on this, and certainly the DPRK (North Korea) have provided a declaration so they cooperate fully on verification efforts," he told reporters Wednesday.

"(But) verification itself will take longer than just a few days, verification will take several weeks or even months. But we need to agree on how verification will work."

The talks began in 2003 with the aim of convincing Kim Jong-Il's regime to abandon the nuclear weapons it had spent decades developing, but they have suffered countless setbacks and delays.

China, host of the talks, on Tuesday expressed confidence that further progress would be made this week.

"We are looking forward to the positive achievements of this meeting of the heads of delegations, so as to promote the ushering in of a new stage of the six-party talks process," foreign ministry spokesman Qin Gang said.

Under the current second phase of the disarmament deal, the North had to disable its plutonium-producing Yongbyon facility and document its nuclear activities in return for energy aid equivalent to one million tons of fuel oil.

After it handed over its declaration, North Korea blew up the cooling tower at Yongbyon, in a dramatic gesture intended to demonstrate its commitment to disarmament.

In response, the United States has eased some trade sanctions and moved towards taking the North off its list of state sponsors of terrorism -- as stipulated under the second phase.

US President George W. Bush softened his hardline stance against North Korea following the 2006 atomic test, and US incentives since offered to Pyongyang for disarming have been a key reason for the recent progress.

Hill said on Wednesday the six parties would also discuss the scheduling of fuel shipments to North Korea during the talks.

The third and final phase of the disarmament deal calls for the North to permanently dismantle its atomic plants and hand over all nuclear material and weaponry.

In return the North would secure diplomatic ties with the United States and Japan, as well as a range of other economic and political rewards.

Hill earlier said he hoped the talks -- tentatively scheduled to last three days -- would also touch on how to address this crucial and final phase.

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