Landmark referendum on sweeping presidential powers underway in Turkey

Polling stations have opened for the controversial constitutional referendum in Turkey. President Recep Tayyip Erdoğan hopes to gain considerably more power through the changes.Critics worry the constitutional changes would grant Erdoğan authoritarian rule until 2029.International elections observers from the OSCE are attending polling stations over worries about possible manipulations of votes. Security at polling stations has also been stepped up after threats made by Isis.