[1/7] A general view of the site of a crash, where two trains collided, near the city of Larissa, Greece, March 1, 2023.
There have been widespread media reports electronic signal software was not working, meaning signalling was done manually.
OSE, the country's state-owned operator for rail infrastructure, did not respond to calls requesting comment nor did it issue a statement.
Within hours, Greek police had arrested the station master at a provincial train station, accusing him of death through negligence.
Hellenic Train, a unit of Italy's Ferrovie dello Stato which acquired passenger and freight operations, said it was working with authorities on the investigation.