Officials have made no suggestion of hostile fire, although an Iraqi rebel group claimed it had shot the plane down.
"It was not shot down," Transport Ministry media director Ahmed Abdul Wahab told Reuters. "It is believed to have been a technical failure but the investigation is continuing," he said.
He added that it crashed near a U.S. base so U.S. authorities were handling the matter and he had no more details.
U.S. military officials said on Wednesday they had no information on the crash.
Turkish officials said the death toll from the crash had risen to 34 and that one survivor was being treated for his injuries in hospital.
The crash occurred when the Moldovan Antonov-26 tried to land in foggy conditions near Balad, north of Baghdad. Most of the 35 people on board were Turkish construction workers.
Cahit Kirac, the governor of Turkey's Adana province from which the Antonov-26 had taken off on Tuesday, said a plane flew to Iraq on Wednesday to bring back the bodies of the dead Turks.
Many Turkish companies have been involved in reconstruction and other infrastructure projects in Iraq since the U.S.-led invasion of the country in 2003. (Additional reporting by Zerin Elci in Ankara)
