The United States has repeated its warning to North Korea against conducting another rocket test, but declined to confirm Japanese media reports that Washington had warned Tokyo of an imminent launch by Pyongyang.

The state department spokesman, James Rubin, said the Americans had made it clear to North Korea that any further test would have serious consequences on their relations.

Japan and the United States were taken by surprise in August when North Korea launched a rocket which went over Japan.

American experts said at the time it was a ballistic missile test, but the North Koreans said it was toput a satellite into orbit.