French President Francois Hollande of France had a slip of the tongue, speaking in French at a news conference in Tokyo.
Referring to the Algerian hostage crisis in January, in which 10 Japanese people were killed, he said he had expressed "the condolences of the French people to the Chinese people".
He did not correct his mistake. However, an interpreter made a correction, in her simultaneous translation.
But the BBC reports at least one Japanese journalist picked up on the error.
Relations between Japan and China are often frosty. Polls in both countries suggest a mutual distrust and neither side's nationals like to be confused with the other.
President Hollande was on a state visit to Japan.
