China and the United States pressed North Korea on Friday to return to talks on ending its nuclear arms programme and called for full implementation of UN sanctions imposed on the country after its October 9 atomic test.

The crisis trip by US Secretary of State Condoleezza Rice to east Asia has been overshadowed by speculation that North Korea might be about to detonate a second nuclear device.

But Chinese officials suggested that their envoy, sent by President Hu Jintao to Pyongyang earlier this week, had made progress in bringing North Korea back into line.

"Fortunately my visit this time has not been in vain," the envoy, Tang Jiaxuan, said at the opening of his meeting with Rice, referring to his trip to Pyongyang. Reporters were then ushered from the room.

Chinese Foreign Minister Li Zhaoxing said Tang and the North Koreans also discussed how to kick-start stalled talks on Pyongyang's nuclear programmes.

"At least it increased mutual understanding. Everyone discussed how to restart progress in the six-party talks as quickly as possible," Li told reporters.

The six-party talks, which bring together the two Koreas, the United States, Japan, Russia and host China, stalled last November after Washington imposed restrictions on Pyongyang's external financing.

At a joint briefing with Rice, Li appealed for calm and a diplomatic solution to the crisis.

"We hope all relevant parties can maintain cool-headedness, adopt a prudent and responsible attitude and stick to the general direction of a peaceful resolution through dialogue," Li said.

Rice told the news conference after talks with Li that North Korea's nuclear test was "a serious provocation" that posed a threat to peace and security, particularly in east Asia.

"We talked about the importance of the full implementation of (UN resolution) 1718 so we can make certain there is not a transit and trade in illegal materials, dangerous illegal materials, concerning the nuclear programme of the DPRK," she said referring to North Korea by its official acronym.

'STRONG MESSAGE'

Rice's visit came one day after Beijing sent Tang to lead a mission to North Korea to deliver what US officials said was a "very strong" message.

South Korea's Chosun Ilbo newspaper quoted an unidentified diplomatic source in Beijing as saying Kim told Tang that Pyongyang would return to stalled six-party talks on ending its nuclear programmes if Washington lifts financial sanctions.

Kim also expressed regret to Tang about the difficult position in which the nuclear test had placed Beijing, it said.

US officials tried to lower expectations about the outcome of the meeting and said they did not expect any major announcement such as a return to the six-party talks.

In her meetings with China's president and foreign minister, Rice would try and allay Beijing's scepticism over some elements of financial and weapons sanctions imposed by the United Nations, making clear the United States did not want to escalate tensions, said a senior State Department official travelling with her.

Rice delivered similar messages to the governments of Japan and South Korea on the first legs of her five-day trip.