A Greek court found the leaders of neo-Nazi party Golden Dawn guilty of running a criminal organisation on Wednesday at the end of a historic trial that was hailed by the prime minister as a victory for democracy.

The judgement in an Athens court came as police and anti-fascist demonstrators clashed outside the courthouse, on the sidelines of a large protest of some 15,000 people.

After a trial lasting over five years, presiding judge Maria Lepenioti said Golden Dawn founder and leader Nikos Michaloliakos and other senior members were guilty of running a criminal organisation.

"Democracy won today," Greek Prime Minister Kyriakos Mitsotakis said in a televised address, adding that the ruling ended a "traumatic" cycle in Greek public life.

The crowd gathered in response to a call from the anti-fascist movement, trade unions and leftist parties
The crowd gathered in response to a call from the anti-fascist movement, trade unions and leftist parties AFP / ANGELOS TZORTZINIS

President Katerina Sakellaropoulou said Wednesday's "historic" ruling "confirmed that democracy and its institutions will always be able to overcome any attempt to undermine them".

Among those convicted was independent European parliamentarian Yiannis Lagos, who defected from the party last year; the party's former spokesman Ilias Kassidiaris who has formed a new far-right party; and a dozen other senior party members elected to parliament in 2012 at the height of Golden Dawn's influence.

None of the party's senior members were present in court.

Michaloliakos and other senior cadres convicted on the criminal organisation charge face jail sentences of between five and 15 years.

Golden Dawn party leader Nikolaos Michaloliakos testifies before the criminal court in Athens on November 6, 2019.
Golden Dawn party leader Nikolaos Michaloliakos testifies before the criminal court in Athens on November 6, 2019. AFP / Aris MESSINIS

In a Twitter post, Michaloliakos said he would "fight to the end" to overturn his conviction.

The sentences are to be announced in separate hearings.

Prosecution lawyers told AFP that the convicts would only be arrested once the court has decided whether their sentences should be suspended pending their appeals.

Hundreds of police were deployed at the courthouse, a few kilometres from the historic centre of the capital, barring the entrance with a wall of police vans.

Some members of the crowd carried anti-fascist placards and shouted slogans denouncing the defendants
Some members of the crowd carried anti-fascist placards and shouted slogans denouncing the defendants AFP / ANGELOS TZORTZINIS

Anti-fascist protests were also held in other Greek cities.

The prosecutions were sparked by the late-night murder of 34-year-old anti-fascist rapper Pavlos Fyssas in September 2013.

He was chased down by a mob of Golden Dawn members and stabbed to death in front of a cafe in the western Athens suburb of Keratsini.

The mother of murdered rapper Pavlos Fyssas also arrived for the verdict
The mother of murdered rapper Pavlos Fyssas also arrived for the verdict AFP / LOUISA GOULIAMAKI

"Pavlos, you did it," the rapper's mother Magda shouted outside the courthouse after the verdict was announced, her hands raised in triumph. She had attended most of the trial's 453 sessions.

His killer, former truck driver Yiorgos Roupakias, had confessed to the crime, but the attack sparked outrage and the charges that Golden Dawn was a paramilitary-style organisation that used beatings, intimidation and murder as tactics -- all with the knowledge of senior party members.

Also convicted on Wednesday, Roupakias faces a life sentence.

Main opposition leader Alexis Tsipras earlier on Wednesday had called for the conviction of a group that had "poisoned society with hatred".

There was uproar last year when chief prosecutor Adamantia Economou called for the acquittal of the party leaders on the basis that the existence of a criminal organisation had not been proven.

Greek courts had for years been unable to keep Golden Dawn from running because laws in the country prohibit the suppression of ideology.

In total, 68 members of the party were on trial, including Michaloliakos and more than a dozen other former MPs like him, elected in 2012 as the openly xenophobic group capitalised on discontent over joblessness and migration.

Fifty of them were convicted of criminal activity. Several among the defendants were also convicted of illegal arms posession.

As well as delivering a verdict in the murder trial for Fyssas and the trial of senior leaders of Golden Dawn, the court handed down judgements for two other assault cases involving Golden Dawn members.

An Egyptian fisherman was left with broken teeth and head injuries after being beaten with clubs and metal bars in June 2012 as he slept.

Just over a year later, Communists putting up posters were attacked with nail-studded clubs.

Golden Dawn was at its political peak at the time of Fyssas's murder, having won 18 seats in the 300-seat parliament in 2012 amid anger over a financial crisis in Greece that discredited mainstream political parties.

In 2014, it sent three deputies to the European parliament, and in 2015 it finished third in national elections with 17 lawmakers.

But the investigation took its toll, causing a number of senior members to defect. In the last election in 2019, the party failed to win a single seat.

The Golden Dawn website, which posted a message of defiance earlier Wednesday, could not be accessed after the verdict was announced.