He said that no new obstacles have emerged following Pyongyang's shutdown of its sole operating reactor.

'I think we're all in the same ballpark,' Assistant Secretary of State Christopher Hill said after a series of meetings with Mr Kim Kye Gwan ahead of resumed nuclear talks in Beijing.

'We had a good discussion - at this point there are no showstoppers,' he told reporters.

Aside from their meetings, the two men enjoyed a spicy lunch at an upscale Sichuan restaurant where talks apparently did not touch on anything nuclear.

Mr Hill repeated his desire to have the North disable its nuclear facilities by the end of the year, following its weekend shutdown of its sole operating reactor.

'I laid out my view on how this could be done, and I think we had a good discussion on that basis,' he said.

He said he would meet the Chinese hosts today before six-party negotiations resume to gauge whether the proposed timeframe was feasible.

The shutdown of the Soviet-era Yongbyon reactor that produces plutonium for use in bombs was North Korea's first step towards halting production of atomic weapons since the nuclear stand-off began in late 2002.

The North conducted its first nuclear test explosion last October.

Talks this week were expected to focus on setting a schedule for North Korea to declare all its nuclear programmes and then disable them so they cannot be easily restarted. The North has pledged in principle to eventually abandon its nuclear facilities.

Before leaving Pyongyang yesterday, Mr Kim said that closing the reactor meant the process was moving into the second phase.

'There should be discussion on how to define the targets of the second phase, the obligations for each party, and also the sequence of the actions,' he said.

South Korean nuclear envoy Chun Yung Woo said the closing of the reactor was important, but only a first step.

'There is a very difficult and steep road ahead of us,' he said on arrival here.

Said Japanese envoy Kenichiro Sasae: 'We need to discuss thoroughly how to push the process forward.'

Inspectors from the International Atomic Energy Agency have verified the reactor closure and were checking other facilities - including two dormant construction sites for reactors - and installing monitoring equipment.

North Korea has begun receiving 50,000 tonnes of heavy fuel oil from South Korea as a reward for the shutdown, and will eventually receive the equivalent of one million tonnes for disabling the facilities.

ASSOCIATED PRESS, AGENCE FRANCE-PRESSE