Turkey's foreign minister says the fighter jet shot down by Syrian air defence forces on Friday had mistakenly strayed into Syrian airspace but was in international airspace when it was hit.
Ahmet Davutoglu said the unarmed plane was not on a secret mission related to Syria, but had mistakenly entered Syrian airspace before the incident.
Syria maintains that it engaged the aircraft in its airspace.
The Turkish and Syrian navies are still searching for the two crew members.
Turkey says the identity of the jet was clear to all and that it was shot down without any warning being given.
Turkey's government has promised that its response will be strong, decisive and legitimate once it has ascertained all the circumstances surrounding the downing of the jet.
In an interview with TRT television on Sunday, Mr Davutoglu asserted that the unarmed F-4 Phantom had entered Syrian airspace by mistake on Friday but had left by the time it was shot down several minutes later.
According to our conclusions, our plane was shot down in international airspace, 13 nautical miles (24km) from Syria, he said.
The BBC reports according to international law, a country's airspace extends 12 nautical miles (22.2km) from its coastline, corresponding with its territorial waters.