10 were killed and 73 were injured after a train came off its rails on Sunday, July 8.
Turkey's ministry of transport said "the ground between the culvert and the rail collapsed" owing to heavy rain.
The state-run Anadolu news agency quoted Akdag as saying search operations this morning had now been completed at the wreck of the train, which derailed early Sunday evening in the Tekirdag region while heading towards Istanbul.
The train was carrying 362 passengers and was headed to Istanbul.
An unnamed survivor said she was riding in one of the cars when it went off the tracks.
Tekirdag governor Mehmet Ceylan blamed "adverse weather conditions" for the accident, adding that the ground was muddy from heavy rain and hard for rescuers to reach.
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Health Minister Ahmet Demircan said 318 people required treatment after the accident with 124 still hospitalized.
Television images showed emergency personnel walking to reach the crash site.
About 100 ambulances were at the scene, along with helicopters from the Turkish army.
The train involved in Sunday's accident appears to have been a slower train on a single track railway. "Many of those injured have been taken off the site".
Meanwhile, President Recep Tayyip Erdogan was informed about the accident by Interior Minister Suleyman Soylu and Minister of Transport, Maritime Affairs, and Communications Ahmet Arslan over the phone, a presidential source said.
CNN Turk has claimed that a collapsed bridge was the cause of the accident.