North Korea's top nuclear envoy will reportedly visit the United States sometime next month.

Diplomatic sources in Beijing say North Korean Vice Foreign Minister Kim Kye-kwan has ended talks with China's chief delegate to the six-party talks in Beijing and is expected to visit Washington to reciprocate a visit U.S. envoy Stephen Bosworth made to North Korea in December.

But observers say if Kim continues to call for a peace agreement and the lifting of sanctions as a precondition to the North's return to the nuclear dialogue while in the U.S., the bilateral talks won't produce much progress.

The sources speculate that China's new chief delegate to the six-way talks, Wu Dawei, could also visit South Korea, the U.S. and Japan to arrange the talks' resumption following the lunar New Year holiday this weekend.