Chinese President Hu Jintao's visit to Tokyo may have to wait until May instead of mid-April because of the increasingly bitter dispute over pesticide-tainted meat-and-vegetable 'gyoza" dumplings from China, government sources said Wednesday.

Government officials are increasingly concerned that a disagreement between Japanese and Chinese police about how the toxic pesticide methamidophos got into the gyoza could damage bilateral ties.

Although neither government has officially announced a date for Hu's visit — except to say "in the cherry blossom season" — the Japanese media have been reporting that both were shooting for around April 15.