During her two-day stay, starting Thursday, Ashton will meet Turkish Foreign Minister Ahmet Davutoglu in Istanbul, where a second round of talks between Iran and the so-called 5+1 group will take place later this month, the statement said.
Davutoglu has said the second round will be held on January 21-22, while Ashton’s office has given January 20 as a tentative date for the start of the meeting.
Negotiations between Iran and the six powers — Britain, China, France, Russia, the United States and Germany — spearheaded by Ashton, resumed in Geneva in December after a 14-month hiatus.
Tehran insists its nuclear programme is solely for peaceful purposes but the United States and its allies suspect that the Islamic republic is secretly developing an atomic bomb.
Ashton and Davutoglu will discuss also Turkey’s struggling bid to join the European Union, the statement said.