More than 2,000 mourners in Greece have bid farewell to an anti-racism rapper, who was stabbed to death by a man sympathising with the far-right Golden Dawn party.

The killing of 34-year-old Pavlos Fissas touched a nerve in Greece, where economic hardship has worsened social tensions, and rallies in several cities to mark his death turned violent late yesterday.

"Pigs! Fascists! Murderers!" mourners chanted as relatives carried Mr Fissas' white coffin into a graveyard on a hill overlooking the working-class Keratsini suburb where he was stabbed.

As others sang his songs, one man shouted: "Immortal!"

Mr Fissas, who went by the stage name Killah P, was stabbed twice in the chest and heart on Tuesday night in a brawl after a soccer match shown in a café.

Several rallies by anti-establishment groups and unions, which turned a 48-hour anti-austerity strike into a protest over his killing, were planned for later.

A self-proclaimed supporter of the fiercely anti-immigrant group confessed to the killing.

The 45-year-old, who has been pictured in Greek media with his arm around a Golden Dawn politician, is to appear before a prosecutor on Saturday.

Golden Dawn, Greece's third most popular party, condemned the killing and denied involvement in the attack. It said those who accused the party were "wretched sycophants" trying to win votes.

The party, with an emblem resembling a swastika, rose from obscurity to win 18 seats in parliament in elections last year on an anti-immigrant and anti-corruption agenda.

Its members have been seen giving Nazi-style salutes, but the party rejects the neo-Nazi label.

Human rights' groups have  accused the party of being linked to attacks on immigrants, but this is the first time it is being investigated for evidence linking it to an attack.

Above a photo of a swastika in a red circle with a line running through it, Greece's top selling daily, Ta Nea, wrote on its front page: "Enough is enough!"

More than 5,000 people rallied in Athens on the spot where Mr Fissas was stabbed.

Police fired teargas at protesters, who hurled stones and petrol bombs at a police station and set rubbish containers on fire.

Clashes between police and demonstrators were also reported in two other cities, Patras and Thessaloniki.