Investigators in Turkey are trying to establish why a high-speed train came off the rails between Istanbul and Ankara, killing at least 36 people.
Some passengers said the train was travelling too fast
The head of Turkey's railway network, Suleyman Karaman, says sabotage was not to blame for Thursday's disaster.
Officials have rejected some reports that the train, with 230 people on board, was going too fast.
The modern express was only recently introduced to serve the busy route despite criticism from engineers.
The packed express derailed near the town of Pamukova, in north-west Turkey, at 1945 local time (1645GMT).
There were chaotic scenes shortly after the accident leading to confusion over the death toll.
The government crisis centre initially put the death toll at 139 - but later revised the figures downwards.
The BBC's Jonny Dymond in Istanbul says the investigations are expected to focus on the rescue, the discrepancy of casualty figures and why the express train system was allowed to go ahead despite the criticism.
There had been claims of compromises made when the new train began running along the modified railway track last month.
But officials insisted the train, en-route from Istanbul to the capital Ankara, was not travelling fast at the time.
The Turkish press attacked the government, calling the incident "murder".
The daily Sabah said it was "an accelerated massacre".
The Milliyet daily said: "They died in the name of a show-off."
Professor Aydin Erel, from Istanbul's Yildiz Technical University, said he had warned the government that the existing tracks were not up to the standard to bear high speeds.
"Our infrastructure was not suitable for such speed," he said. "Our warnings were ignored."
On Friday, heavy equipment started removing the wreckage of the overturned carriages.
In hospitals, where the injured were being treated, passengers relived the horror of the accident.
"It was suddenly all dust and smoke and we overturned," said Hatice Er. "It was like an earthquake."
Another injured passenger, Namik Kemal Ozden, said the train was "a little fast going around the curves".
"There were vibrations," he said. "My cousin was sitting next to me, we hugged
each other. The windows broke and we fell to one side. We could only understand what happened once we got out."
Prime Minister Recep Tayyip Erdogan cancelled a visit to Bosnia-Hercegovina to visit the scene.
Our correspondent says such incidents are rare in Turkey, where railways are not used as a major form of transport.