CNN Türk television said Turkey was in contact with the Syrian authorities to get permission to conduct a search for the airmen, although there was no immediate official confirmation.
In a statement, Turkey's military said a search and rescue operation was underway. It lost radar and radio contact with the plane after it took off from Erhac Airport in the eastern province of Malatya, which borders Syria.
Two crew were aboard the F-4 at the time of the crash, the Turkish state news agency Anatolia said, citing Malatya governor Ulvi Saran.
Pro-Iranian Al-Mayadeen television station, which is based in Lebanon, quoted what it said were Turkish sources as saying a jet had been shot down by Syrian air defences near the border with Turkey. There was no confirmation of that report.
