Four journalists brought to Turkey after being held captive for months in Syria leave for France on a French Air Force plane.
Gul expressed his condolences and condemned the attack on the American consulate in Benghazi which killed US Ambassador Christopher Stevens and four other Americans.
The Turkish Foreign Ministry has also condemned an attack on Ambassador Stevens and three other Americans.
Sub-sea tunnel will connect Asian and European sides of the Bosphorus Strait, enabling a 15-minute crossing.
Arinc says current president Gul to support Erdogan's candidacy.