Greek's prime minister, Antonis Samaras, has condemned the neo-Nazi Golden Dawn party over the fatal stabbing of a leftist hip-hop artist which has sparked a wave of protests and deamnds to outlaw the far-right group.

As more than 2,000 people mourned the anti-fascist rapper Pavlos Fyssas, known by the stage name of Killah P, Samaras pledged his personal "no pasaran" ("They shall not pass") on Golden Dawn.

"This government is determined not to allow the descendants of the Nazis to poison our social life, to commit crimes, terrorise and undermine the foundations of the country that gave birth to democracy," Samaras said in a televised address.

Angry mourners chanted "Pigs! Fascists! Murders" as the white coffin of Fyssas was carried into a graveyard in the western Athens suburb of Keratsini where he had been stabbed to death after an argument with a 45-year-old self-proclaimed Golden Dawn member.

Although Golden Dawn, Greece's third most popular party, denied any involvement, numerous voices have demanded that it be outlawed.

Minister of public order Nikos Dendias said the government would consider new laws on armed gangs, meaning the neo-Nazi party could be classified as a criminal group.

Blogger Nikos Xydakis argued in Greek newspaper Ekathimerini that the country had hit its "red line" over Golden Dawn. The PanHellenic Socialist movement, which is part of the governing coalition, called for the party to be banned.

Samaras did not announce specific measures. "The descent into violence destroys any prospect for Greece to achieve development, peace and prosperity," he said.

Clashes between leftwing activists and riot police erupted in Athens and other cities after thousands of Greeks took to the streets to protest against the murder.