ATHENS, Greece (AP) A stationmaster accused of causing Greeces deadliest train disaster was charged with negligent homicide and jailed pending trial Sunday, while Prime Minister Kyriakos Mitsotakis apologized for any responsibility Greeces government may bear for the tragedy.

An examining magistrate and a prosecutor agreed that multiple counts of homicide as well as charges of causing bodily harm and endangering transportation safety should be brought against the railway employee.

At least 57 people, many of them in their teens and 20s, were killed when a northbound passenger train and a southbound freight train collided late Tuesday north of the city of Larissa, in central Greece.

The 59-year-old stationmaster allegedly directed the two trains traveling in opposite directions onto the same track. He spent 7 1/2 hours Sunday testifying about the events leading up to the crash before he was charged and ordered held.

My client testified truthfully, without fearing if doing so would incriminate him, Stephanos Pantzartzidis, the stationmasters lawyer, told reporters. The decision (to jail him) was expected, given the importance of the case.

Pantzartzidis implied that others besides his client share blame, saying that judges should investigate whether more than one stationmaster should have been working in Larissa at the time of the collision.

For 20 minutes, he was in charge of (train) safety in all central Greece, the lawyer said of his client.

Greek media have reported that the automated signaling system in the area of the crash was not functioning, making the stationmasters mistake possible. Stationmasters along that part of Greeces main trunk line communicate with each other and with train drivers via two-way radios, and the switches are operated manually.

The prime minister promised a swift investigation of the collision and said the new Greek transportation minister would release a safety improvement plan. Once a new parliament is in place, a commission also will be named to investigate decades of mismanagement of the countrys railway system, Mitsotakis said.