The station master involved in Greece's worst-ever train disaster had his court appearance postponed by a day Saturday as the country braced for more mass protests over the crash that killed at least 57 people.

Thousands of protesters have demonstrated across the nation since Tuesday's collision between a passenger train and a freight train, with public anger mounting over government failure to manage the rail network.

More demonstrations were expected in several major cities Saturday, and a large rally of students and railway employees was set for Sunday in the capital's Syntagma Square, adjacent to parliament.

"What happened was not an accident, it was a crime," said Sophia Hatzopoulou, 23, a philosophy student in Thessaloniki.

"We can't watch all this happen and remain indifferent."

The train was carrying many students returning from a holiday weekend and at least nine young people studying at Thessaloniki's Aristotle University were among the dead, while another 26 others were injured.

The station master at Larissa, central Greece, has admitted responsibility for the accident, which saw the two trains run along the same track for several kilometers.

The 59-year-old was due to appear in court Saturday where he could face charges of negligent homicide but will now appear Sunday, his lawyer said. He risks life in jail if found guilty, but his lawyer has argued that other factors were at play.

"In the case, there are important new elements that need to be examined," his lawyer Stefanos Pantzartsidis said.

Public broadcaster ERT reported the station master had been appointed to the post only 40 days earlier -- and after just three months' training.

The man, whose identity has not been made public, was apparently alone at the station without any supervisor, according to the Kathimerini Daily, despite it being a holiday weekend with high demand and heavy rail traffic.