(FILES) This file photo taken on February 18, 2017 shows participants waving Turkish flags during an event with the Turkish Prime Minister to promote a constitutional referendum in Oberhausen, western Germany. Turkish politicians will hold no further rallies in Germany ahead of April's referendum on expanding President Recep Tayyip Erdogan's powers, his AKP party said on March 20, 2017 amid a heated diplomatic row. / AFP PHOTO / Sascha Schuermann