ATHENS, Greece -- Tens of thousands of people marched in Athens and cities across Greece on Wednesday to protest the deaths of 57 people in the country's worst train disaster, which exposed significant rail safety deficiencies.
Labor unions and student associations organized the demonstrations, while strikes halted ferries to the islands and public transportation services in Athens, where at least 30,000 people took part in the protest.
Clashes broke out after the rallies in Athens and two other cities.
More than 20,000 people joined rallies in Thessaloniki, Greece's second-largest city, where several dozen youths challenged a police cordon. Twelve students from the city's university were among the dead in last week's head-on crash between two trains.
Police fired tear gas in the southern city of Patras, where a municipal band earlier played music from a funeral march while leading the demonstration. In the central city of Larissa, near the scene of the train collision, students holding black balloons chanted "No to profits over our lives!"
The accident occurred on Feb. 28 near the northern Greek town of Tempe. A passenger train slammed into a freight carrier coming in the opposite direction on the same line, and some of its derailed cars went up in flames.
A stationmaster accused of placing the trains on the same track has been charged with negligent homicide and other offenses, and the country's transportation minister and senior railway officials resigned the day after the crash.
But revelations of serious safety gaps on Greece's busiest rail line have put the center-right government of Prime Minister Kyriakos Mitsotakis on the defensive. He has pledged the government's full cooperation with a judicial inquiry into the crash.
"This is more than a train collision and a tragic railway accident. You get the sense that the country has derailed," Nasos Iliopoulos, a spokesperson for Greece's main left-wing opposition party, Syriza, said.
Senior officials from a European Union railway agency were expected in Athens as part of promised assistance to help Greece improve railway safety. The agency in the past publicly highlighted delays in Greece's implementation of safety measures.
Safety experts from Germany also were expected to travel to Greece to help advise the government, Greece's new Transport Minister George Gerapetritis said.
"I, too, express my anguish and heartbreak over what happened in Tempe. This is an unprecedented national tragedy, which has scarred us all because of the magnitude of the tragedy: this unjustified loss of a great number of our fellow human beings," Gerapetritis said.
Information for this article was contributed by Thanassis Stavrakis and Costas Kantouris of The Associated Press.
Gallery: Tens of thousands march in Greece to protest train disaster