Protests have erupted in Greece over the rail crash which killed 43 people, with many seeing it as an accident that had been waiting to happen.

Rioters clashed with police outside the headquarters of Hellenic Train in Athens - the company responsible for maintaining Greece's railways.

Protests were also held in Thessaloniki and the city of Larissa, near where the disaster happened on Tuesday night.

The government has said an independent investigation will deliver justice.

Three days of national mourning have been declared across the country following the incident, in which a passenger service crashed head on into a freight train, causing the front carriages to burst into flames.

The front carriages of the passenger train were mostly destroyed.

Prime Minister Kyriakos Mitsotakis said "tragic human error" was to blame for the disaster.

A 59-year-old station master in Larissa has been charged with manslaughter by negligence. He has denied any wrongdoing, blaming the crash on a technical fault.

Rail union members believe safety systems were not working properly, with repeated warnings about this over many years.

In protest and mourning, rail workers are planning on striking on Thursday at what they say is official neglect of the railways.

"Pain has turned into anger for the dozens of dead and wounded colleagues and fellow citizens," the workers' union said in a statement announcing the strike.

"The disrespect shown over the years by governments to the Greek railways led to the tragic result," it added in comments cited by Reuters news agency.

Transport Minister Kostas Karamanlis resigned over the disaster, saying he would take responsibility for the authorities' "long-standing failures" to fix a railway system he said was not fit for the 21st Century.

But outside a hospital where bodies of the train crash's victims were being brought, a banner was hung claiming that any systemic failings would be covered up in the official investigation now under way.

At a silent vigil in Larissa on Wednesday to commemorate the victims of the incident, one demonstrator said he felt the disaster had only been a matter of time.

"The rail network looked problematic, with worn down, badly paid staff," Nikos Savva, a medical student from Cyprus, told AFP news agency.

The station master arrested should not pay the price "for a whole ailing system", he added.

"This is an inadmissible accident. We've known this situation for 30 years," a doctor based in Larissa, Costas Bargiotas, told AFP.

A vigil was also held in Athens, outside the offices of Hellenic Train. Later in the day, things turned violent in the same area, with police using tear gas to disperse protesters who threw stones and lit fires in the streets.

At the site of the country's worst ever train crash, rescuers yet again worked through the night.

Families have been arriving at a nearby hospital to give DNA samples so that their missing loved ones may be identified.

But this will become an increasingly difficult process as more remains are retrieved of those who were at the front of the passenger train and who bore the full force of the head-on collision and the fire that then ripped through their carriages.

Fire brigade spokesperson Vassilis Varthakogiannis said temperatures inside the first carriage had reached 1,300C (2,370F), which made it "hard to identify the people who were inside".