Under the six-party talks hosted by China, North Korea agreed in September 2005 to abandon its nuclear programme.

The talks, which include envoys from North and South Korea, China, Japan, Russia and the US - broke down at the end of last year with Pyongyang saying the process was dead.

The North conducted a second nuclear test in May, and announced it was scrapping all deals made under the six-party process, under which it was to give up its nuclear ambitions in exchange for economic and diplomatic benefits.

North Korean visit

Bosworth's visit comes as a high-level North Korean official is visiting Beijing for talks, raising hopes that the stalled talks can be resumed.

US officials say Bosworth has no plans to meet North Korean officials in Beijing [Reuters]

Jiang Yu, the Chinese foreign ministry spokeswoman, told reporters that Kim Yong-il, the North Korean vice foreign minister arrived on Tuesday to mark 60 years of diplomatic ties between the countries.

The visit is significant because Beijing is Pyongyang's chief source of diplomatic support and assistance to its impoverished economy.

The trip comes two weeks after Chinese nuclear envoy Wu Dawei visited Pyongyang.

North Korea has made a series of conciliatory gestures that some analysts have interpreted as a possible softening of its position towards its neighbour South Korea and international powers.

China has argued against tough measures by the international community that could further exacerbate tensions, while calling for a resumption of the nuclear talks.

"As the situation in northeast Asia has recently shown signs of thawing, we expect all parties involved in the Korean nuclear talks to seize this opportunity to continuously transform the situation," Jiang said on Tuesday.