ISTANBUL (Reuters) - President Tayyip Erdogan will discuss with Tehran their response to the Iraqi Kurdish independence referendum when he visits Iran next week with the Turkish chief of staff, Prime Minister Binali Yildirim said on Monday. Yildirim s comments, in an interview broadcast on multiple Turkish television channels, came after Erdogan spoke by phone on Sunday with Iranian President Hassan Rouhani and voiced concern that the referendum will cause regional chaos. Erdogan is due to visit Iran on Oct. 4. 