A local railway station manager in Larissa, the town through which the passenger train had been in transit, has been arrested. The 59-year-old has been charged with manslaughter by negligence and causing grievous bodily harm by negligence, said police.
The initial conclusion of an investigation into the crash pointed to human error, according to Greece's Hellenic Railways Organisation (OSE). However, another person at Larrisa station blamed the accident on a possible technical failure, reports the BBC.
Transport Minister Kostas Karamanlis resigned yesterday, saying he felt it was his "duty" to step down "as a fundamental sign of respect for the memory of the people who died so unfairly".
Greek Prime Minister Kyriakos Mitsotakis, who visited the scene of the accident on Wednesday, vowed to find out what happened and make sure it never happens again.
Greek firefighters have said that the identification of people is proving to be 'very difficult' because of temperatures in excess of 1,300°C at the site of the fire.
As an addition to the 43 people who have so far died, dozens of others have been injured.