Clashes have broken out between police and protesters near the site of a the fatal stabbing of a left-wing activist and rapper, blamed on a supporter of the far-right Golden Dawn party.
The clashes came during a demonstration being held to protest at the killing of Pavlos Fyssas, a 34-year-old musician known as rapper Killah P.
A 45-year-old man arrested for the attack has admitted to the stabbing, and of being a member of Golden Dawn, a far-right party who won nearly 7% of the vote in the last general election.
Europe Correspondent Emma Murphy reports.
Golden Dawn, whose members have expressed admiration for Adolf Hitler, have grown in popularity as Greece has been gripped by a punishing schedule of austerity measures.
Unemployment stands at a 28%, and the number of young people out of work stands at 59%, according to the European Commission.
Recent opinion polls show support for the party has grown to 12% since the last election.
Party members and supporters, often clearly identifiable in black T-shirts and combat trousers, have been blamed for beatings and stabbings across the country.
Senior figures in the party have also frequently engaged in outbursts and name-calling in parliament, most recently insulting Muslim MPs as Turkish agents.
Golden Dawn said party offices in the western city of Patras and on the island of Crete were attacked by people throwing petrol bombs.