Protestors clash with anti-riot police in Keratsini, Sept. 18, 2013. Clashes between protesters and police officers have been spread all over Keratsini, Peiraius, due to the murder of Greek anti-fascist rapper Paul Fyssas last night, which is related to the neo-fascist Chryssi Avgi (Golden Dawn) party. People have gathered at the spot where the murder took place, yelling and shouting against both Golden Dawn party and the police forces. (Xinhua/Marios Lolos)

Protesters and police clashed on Wednesday evening during a series of anti-fascist demonstrations staged at a Piraeus port neighborhood, where the fatal stabbing of a Leftist activist by an extreme-Right party member occurred earlier in the day, as well as other cities across Greece.

Thousands of demonstrators participated in rallies held in protest at the killing of 34-year-old musician Pavlos Fyssas in one of the worst cases of mounting political violence in the debt-laden country in recent months.

Groups of protesters throwing rocks and petrol bombs on fire near the local police station at Keratsini suburb clashed with anti riot policemen who responded by firing tear gas.

Dozens of bank branches and stores have been damaged, but no severe injuries have been reported, according to police sources.

The President of the Right-wing Independents Party Panos Kammenos who attended the rally organized by Left parties was pushed away by a group of protesters, according to reports.

Similar events of demonstrators clashing briefly with police have been reported during smaller rallies staged at the northern city port of Thessaloniki and a dozen other major cities.

Meanwhile, political leaders condemn the fatal attack and the conservative-led coalition government pledges to push through legislation foreseeing harsher penalties for political motivated violent acts.

Fyssas was stabbed to death early Wednesday outside a cafeteria during a heated argument over a football game and politics among two dozen Leftist activists and far-Right supporters.

Yorgos Roupakias, a 45-year-old employee at the local fish market and father of two, was arrested shortly afterwards and according to police confessed to the fatal attack and his affiliation with the neo-fascist Chryssi Avgi (Golden Dawn) party.

The tragedy triggered a wave of strong statements by political parties, trade unions and ordinary Greeks, as police continues the investigation with raids to Golden Dawn party offices.

Greek President Karolos Papoulias expressed Greek society's outrage at the killing, calling for the creation of a united front to combat fascism.

Golden Dawn still rejects any link to the attack, as it has happened in all previous cases of violent attacks against Left party members and immigrants by its members, including several of its 18 MPs.

Despite increasing violent incidents, more and more Greeks, disgruntled with harsh austerity introduced to tackle an acute debt crisis since 2010, seem to be swayed by the populist and xenophobic rhetoric, according to the latest opinion polls.