The Federal Bureau of Investigation said yesterday it is warning local police about the danger of apocalyptic violence by white supremacist groups spurred by the dawn of the year 2000. In a statement, the FBI said it had wrapped up Project Megiddo, a study of potential crimes by individuals or domestic groups who attach special significance to the year 2000. The study highlights the dangers of fringe white supremacists who seek to initiate a race war, it said. It was being distributed to law enforcement personnel nationwide.