The Turkish warplane shot down by Syria's air defense forces might have violated Syrian airspace, Turkish President Abdullah Gul said on Saturday.
"It is routine for jet fighters to sometimes fly in and out over [national] borders... when you consider their speed over the sea," Gul told the state-run Anatolia news agency. "These are not ill-intentioned things but happen beyond control due to the jets' speed."
Syria has said the plane, an F-4 Phantom, was dealt with "according to the laws that govern such situations," and that it crashed in the Mediterranean Sea.
The jet disappeared over the Mediterranean, near the Syrian coast, about 09:00 GMT on Friday.
Gul said he had had telephone contact with Damascus, and that the search operation for the two pilots was underway.
Relations between NATO-member Turkey and Syria have declined dramatically since the uprising against Syrian President Bashar al-Assad began in March last year. The border between the two countries is "awash" with Syrian refugees and rebel fighters, the al Arabiya television channel said.
Turkey has denied it is shipping weapons to the rebels, following a report by the New York Times that CIA officers in Turkey were vetting arms deliveries to the Syrian opposition.
In Ankara on Saturday, Gul said it Turkey could not ignore the fact that Syria had downed a Turkish aircraft.
"It is not possible to cover over a thing like this, whatever is necessary will be done," Gul said.
Prime Minister Recep Tayyip Erdogan has said Turkey would take all necessary steps once all details of the incident are established.
