Thousands of Greeks, marking the 40th anniversary of the Athens Polytechnic uprising – an event that would trigger the end of military rule in Greece – took to the streets on Sunday after socialist militants claimed responsibility for the murder of two members of the extremist Golden Dawn party.

As demonstrators prepared to commemorate the symbolic date, a previously unknown group of anti-establishment leftists raised the political temperature by vowing to relocate the far-rightists to "the dustbin of history".

"The Militant People's Revolutionary Forces assumes responsibility for the political executions of … the neo-Nazis," said the gang in an 18-page proclamation sent to a local news portal.

"The armed attack-response … is the starting point of the people's campaign to send the neo-Nazi scum of Golden Dawn where they belong, the dustbin of history."

Amid heightened fears of escalating violence in the debt-stricken country, the assailants described the drive-by shootings as retribution for the fatal stabbing of Pavlos Fyssas, a leftwing rapper killed by a self-confessed Golden Dawn supporter in September. And, in chilling language, warned more attacks would follow.

"The revolutionary movement has to proceed with the material destruction of the infrastructure of Golden Dawn and in a coordinated [fashion] attack those who belong to it … their heads should be cracked open with a hammer, their hands cut off, by way of example, with a sickle."

Some 8,000 policemen were seconded to patrol the boulevards of Athens as a sea of Greeks paid tribute to those killed when the military junta sent a tank crashing through the polytechnic's gates to repress a student revolt.

At least 24 are believed to have died in the bloody suppression with most of the casualties among the 150,000 non-student civilians who had converged on the streets outside the campus in an unprecedented display of opposition to the regime.

For a nation that has become increasingly polarised in the midst of economic crisis, the event is a defining moment, hallowed in the minds of many as the catalyst of the collapse of seven years of military rule only decades after a brutal left-right civil war.

"The mood this year is very similar to 1973 when there was a feeling that the junta was disintegrating and people were full of expectation," said Panos Garganas, a prominent leftist and editor of the newspaper Workers Solidarity.

"After five years of worsening levels of austerity and poverty there is a sense that things are coming to an end, that the situation cannot continue," he told the Guardian as he marched through the streets. "We give the government six months at most."

Dissatisfaction with an administration called to enforce deeply unpopular spending cuts in return for international funds to prop up the country's moribund economy has been reflected in rising support for the radical left main opposition Syriza party.

A poll released on Saturday showed the neo-fascist Golden Dawn also gaining in strength in the aftermath of the November 16th attack, which saw two of its members gunned down outside a local party branch in Athens.

Despite accusations of being a criminal organisation – and a government crackdown that has seen its leader and two other deputies imprisoned pending trial – backing for the anti-immigrant group grew by 2.2 percentage points over the past month. With 8.8% of the vote, the far-rightists remained Greece's third biggest political force according to the survey conducted by Alcofor for the weekly Proto Thema newspaper.

As in 1973, radio broadcasts were boomed from the campus on Sunday – only this time by fired employees from the former public broadcaster ERT denouncing the belt-tightening policies of prime minister Antonis Samaras and his two-party coalition.

The protest march, which traditionally ends at the US embassy to denounce Washington's controversial support for the regime, followed two days of unusually poignant commemorations at the polytechnic, with politicians, unionists and ordinary Greeks laying wreaths at the site.

"With our country basically under foreign occupation, the slogans and lessons of the uprising are as relevant today as they were back then," said Christina Minassa, selling leftist literature at a stall outside the campus. "The battle against fascism goes on. In Greece those on the left have suffered greatly."

President Karolos Papoulias, who has become an increasingly vocal critic of the austerity meted out by the EU and IMF in exchange for aid, called the student rebellion "deeply didactic".

"The way in which they laid claim to the freedom of all of us … is deeply didactic," he said. "Their battle was decisive and dynamic but peaceful, they didn't promote violence, they suffered violence," he said in a clear reference to the resurgence of political violence now haunting the country.