File -- In this Friday, Oct. 26, 2007 file photo, Palestinian President Mahmoud Abbas, attends Muslim prayers at a mosque adjacent to his office in the West Bank city of Ramallah. Abbas called the Holocaust "the ugliest crime humanity has known in modern history." His comments, published Sunday by the Palestinian official news agency WAFA, marked a rare acknowledgment by an Arab leader of Jewish suffering during the Nazi genocide. Some 6 million Jews perished in the Holocaust. (AP Photo/Muhammed Muheisen, File)