Paris - French detectives were sceptical yesterday about videotape pictures published by British newspapers of a white car they said might have been involved in a collision with Princess Diana's Mercedes shortly before she was killed on August 31st. The Mirror and Daily Mail published pictures of a white Citroen AX parked outside the Ritz Hotel in Paris on the night the princess died, saying it could be the "mystery" car French prosecutors have been seeking, and not a Fiat Uno. But police here said yesterday that only a white Fiat Uno could have been involved and said the video was "very vague."