Greek Prime Minister, Kyriakos Mitsotakis, has pledged absolute transparency in the probe into Greece's deadliest rail crash that killed 57 people, a day after mass protests rocked the country.

Speaking at the start of his first cabinet meeting since the February 28 accident, Mitsotakis pledged absolute transparency in the investigation to uncover errors.

He also promised immediate actions to improve the problematic situation in the railways, stressing that he would move heaven and Earth to ensure improvements to safety systems were completed.

"We are all responsible for this, we must be brave enough to admit it," said Mitsotakis -- who is fighting to be elected at polls within months -- in televised remarks.

The conservative leader said he felt "rage and shame" when he heard conversations between the local station master, who allegedly accidentally directed the trains onto the same track, and other railway staff.

But he also apologised again and said that "we... must not hide behind a series of human errors".

The Prime Minister stated that the crash happened when a passenger train and a freight train collided head-on in central Greece after mistakenly being directed onto the same track.

Mitsotakis revealed that the government of the country takes full responsibility for the accident, noting that he felt the rage and shame, when he heard conversations between the local station master, who allegedly accidentally directed the trains onto the same track.