Honda Motor Co could put off launching its clean diesel cars in Japan and the United States beyond 2009, a spokesman at Japan's No.2 carmaker said on Thursday.

A sharper rise in diesel fuel prices compared with gasoline and weaker vehicle demand means consumers may not benefit from a rollout next year, he said. Difficulty in lowering costs for the advanced engine could also work against the timeline, he said.

"We have to proceed cautiously in this environment," he said, adding that no official decision to delay the launch had been made.

Honda has said it would introduce clean-diesel cars that would meet strict emissions regulations in Japan and the United States next year. Its latest diesel-powered version of the Accord sedan went on sale in Europe in June.