There were violent clashes between police and students in Athens on Thursday.
The Greek high-school and university students were marching on the fourth anniversary of the death of a 15-year-old Alexis Grigoropoulos who was shot by police.
Students said the march this year also expressed opposition to the government’s tough austerity measures.
The protesters threw rocks and petrol bombs at police who retaliated with tear gas.
Around a dozen protesters were arrested.