The new round of talks on Iran's nuclear program between six world powers and Iran enters the final day in Istanbul on Saturday.
Catherine Ashton, the high representative of the European Union for foreign affairs and security policy, is heading the P5+1 (five permanent members of the UN Security Council including the United States, Russia, China, Britain and France, plus Germany).
Saeed Jalili, secretary of Iran's Supreme National Security Council, is heading the Iranian delegation in the meeting.
The nuclear talks take place in Ciragan Palace. It is uncertain whether any progress will be made through negotiations since both sides dug in around old positions.
Turkish Foreign Minister Ahmet Davutoglu said Friday that the negotiations on Iran's nuclear program were not an issue to be watched from outside.
However, diplomatic sources said that representatives of the nuclear talks will hold a press conference after the close-door meeting.
The first meeting between Iran and P5+1 took place in Geneva, Switzerland in October 2009.