Vanna Mendaleni is a middle-aged Greek woman who until now has not had vehement feelings about the crisis that has engulfed her country. But that changed when the softly spoken undertaker, closing her family-run funeral parlour, joined thousands of protesters on Thursday in a mass outpouring of fury over austerity policies that have plunged ever growing numbers of Greeks into poverty and fear.

"After three years of non-stop taxes and wage cuts it's got to the point where nothing has been left standing," she said drawing on a cigarette. "It's so bad families can no longer afford to even bury their dead. Bodies lie unclaimed at public hospitals so that the local municipality can bury them."

As Greece was brought to a grinding halt by its second general strike in less than a month, Mendaleni wanted to send a message to the Greek prime minister, Antonis Samaras, and other EU leaders meeting in Brussels.

"We once had a life that was dignified. Now the country has gone back 50 years and these politicians have to be made aware that enough is enough."

Greek demonstrations are not now marked by the vehemence or violence of the mass protests that occurred when Europe's debt drama erupted in Athens, forcing the then socialist government to announce pay and pension cuts, tax increases and benefit losses that few had anticipated. Anger and bewilderment have been replaced by disappointment and despair.

But the quiet fortitude that has been on display could soon run out in the country on the frontline of the continent's worst crisis since the second world war. For on Thursday demonstrators were sure of one thing: if pushed too far they may be pushed over the edge.

"Personally, I'm amazed there hasn't been a revolution," said Panaghiotis Varotsos, a computer programmer.

"In Portugal they're rioting over one measure when here we've been made to accept countless cuts and tax increases. And the worst thing about being ground down is that it breeds extremism," said the silver-haired leftist. "In the case of Greece it is extremism that is going to the right because [the neo-Nazi party] Golden Dawn has managed to exploit people's despair. But it won't just stay here. It will spread, like this economic crisis, to other parts of Europe, too."

For the vast majority of those who took to the streets, the tipping point could be the latest round of austerity measures being demanded of the debt-stricken country in return for the international rescue funds it so desperately needs to keep bankruptcy at bay.

Under intense pressure from international creditors at the EU and IMF, Samaras' fragile coalition has been forced to draw up a draconian package of spending cuts worth €13.5bn – the price of a whopping €31.5bn loan instalment that is already four months overdue. Officials have suggested the burden will fall on society's most vulnerable with pensioners and low-income Greeks once again having to make the biggest sacrifices.

"After nearly 50 years of work and paying into an expensive pension fund, I have been forced to retire on €1,000 a month and if they pass these measures it will be even less," said 60-year-old Nikos Xeros, who until this year had repaired ships since the age of 16. "It's like having a noose about your neck that is getting ever tighter. The next time I come out to demonstrate it's going to be with a gas mask and a big wooden club."

Law enforcement officials cut off access to Syntagma Square – home of the Greek parliament – before protesters could reach it, stoking widespread fury on Thursday. For some it was evidence of the mounting fears that parliament could be stormed.

"Greeks are becoming increasingly conscious … and it was especially noticeable that the main slogan today was 'the time has come to overthrow these polices'," said Tania Karayiannis of the union of civil servants. As many as 80,000 people participated in the protests in Athens alone, she said. "The political leadership of this country should not underestimate that. If they don't take our opposition seriously they will bear historic responsibility for the disintegration of Greece's social fabric and the developments that will surely follow."