The prosecutor in a landmark Greek murder trial involving neo-Nazi party Golden Dawn sparked outrage in court Wednesday when she called for the acquittal of the group's leaders.

Prosecutor Adamantia Economou told the court it could not be established that Golden Dawn leader Nikos Michaloliakos or over a dozen other senior party figures had ordered the murder of anti-fascist rapper Pavlos Fyssas in 2013.

The victim's mother reacted angrily when, in a statement read to the chamber, Econmou said Fyssas' fatal stabbing by an alleged Golden Dawn member, Yiorgos Roupakias, had not been premeditated.

Fyssas' murder outside a cafe in an alleged ambush by Golden Dawn supporters shocked the country and opened the way to an unprecedented investigation into the group's operations.

Michaloliakos is one of nearly 70 defendants who each face between five to 20 years in prison over the 2013 killing and other alleged crimes by Golden Dawn members.

The main charge against them is participation in a criminal organisation, but there have also been a host of other indictments related to murder and assault.

Prosecutor Adamantia Economou said it could not be established that neo-Nazi party Golden Dawn leader Nikos Michaloliakos (R, pictured January 2017) had ordered the murder of an anti-fascist rapper
Prosecutor Adamantia Economou said it could not be established that neo-Nazi party Golden Dawn leader Nikos Michaloliakos (R, pictured January 2017) had ordered the murder of an anti-fascist rapper AFP / ANGELOS TZORTZINIS

Holocaust denier and protege of Greece's former dictator Georgios Papadopoulos, Michaloliakos has consistently maintained his innocence. He says the party was persecuted by the government for its popularity during the Greek economic crisis.

Based on records of phone conversations between Golden Dawn members the night Fyssas was murdered, investigating magistrates had argued the attack was carried out with the knowledge of senior party members.

They say it was part of a broader pattern of violence organised by the party against migrants and political opponents -- including beatings of Egyptian fishermen in 2012 and communist trade unionists in 2013.

At the height of its popularity in 2015, Golden Dawn was Greece's third-strongest party, winning more than 370,000 votes.

But its fortunes collapsed in July's general election. For the first time in seven years, it failed to win a parliamentary seat.

A verdict is expected early in 2020.