Protesters gather during a rally against a new austerity package at Constitution (Syntagma) square in Athens May 29, 2011. The protest was organized for a fifth day through a Facebook group called "The Indignant" following similar demonstrations in Spain. [Photo/Agencies]

ATHENS - European and IMF officials are expected to deliver their verdict this week on Greece's faltering drive to bring its budget deficit under control, but ordinary Greeks have warned that their patience is running thin.

Tens of thousands packed a central Athens square on Sunday in a non-partisan protest to denounce the nation's entire ruling class, but they also directed their anger at the International Monetary Fund and its demands for yet more austerity.

Black-hooded youths have been battling police since last year, when the government launched austerity measures under the terms of a 110 billion euro ($157.5 billion) rescue for Greece organised by the IMF and European Union.

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But the Greeks who took Syntagma Square, in front of the Greek parliament, on Sunday were a different kind of protesters.

They were families, ranging from the elderly to children, who had no class wars to wage.

Prompted by Facebook rather than opposition parties or unions, they vented at Greek politicians and foreign lenders.

"We should take responsibility for our own lives," read one banner.

Despite a party atmosphere, the crowd at Sunday's rally -- the biggest in a series of nightly demonstrations on the square for the past five days -- booed, whistled and chanted "Thieves! Thieves" as they pointed at the parliament building.

Protesters acknowledged they had been inspired by similar rallies in Spain, which also faces budget and debt problems.

Before the Syntagma Square rallies began, some Spanish protesters had accused ordinary Greeks of being too passive.

But on Sunday Ifigenia Argyrou, a 57-year-old insurance consultant, said all that had changed.

"People were indignant but they needed a motivation to express that. The Spanish people gave us that motivation," she told Reuters. "We are not sleeping, we are awake. The IMF should get out. There are other solutions without them."

Police put Sunday's crowd at 30,000 although the protesters, who have few formal leaders and are prompted by Facebook, say official figures usually underestimate the size of demonstrations by a wide margin.

Socialist Prime Minister George Papandreou had been due to rally his party on Monday behind yet deeper austerity to win new international aid. But his PASOK cancelled the executive council meeting on Sunday without a detailed explanation.

Papandreou has already failed to win backing from the opposition to adopt fresh austerity steps, more economic reforms and faster sales of state assets, as demanded by the EU and IMF.

With the team of EU and IMF officials in Athens expected to complete its review of Greek finances soon, Papandreou also needs to prevent fatigue from spreading to his own socialist party as its popularity declines.

Papandreou's PASOK has a comfortable majority in parliament but one weekend opinion poll showed it had lost its lead for the first time since it won elections in 2009.

Greeks are angry about they impunity of politicians they hold responsible for the crisis, as well as the dire state of the economy and waves of austerity demanded under international bailout.

Under that plan, Greece was supposed to resume borrowing on financial markets next year but that now seems increasingly unlikely, so the EU is preparing a new aid plan that would meet Greece's funding needs in 2012 and 2013.

In return, the EU wants Athens to impose yet more austerity and reform, including privatisations. The officials are checking Greece's fiscal progress to approve a 12 billion euro aid tranche -- the fifth under the current bailout -- and possibly new funding the country needs to avoid debt default.

German weekly magazine Spiegel fanned fears over the weekend Greece might not get the money, saying the country might have missed all fiscal targets set by its lenders.

Both Greece and the IMF denied the report, while Greek Finance Minister George Papaconstantinou was upbeat on the budget negotiations.

"We expect that they will conclude successfully in the next few days," he said in a statement.

Pressure continues to pile on the socialist government with the EU commission's top economics official Olli Rehn saying time was running out for Greece to secure political agreement on an economic adjustment programme to exit a debt crisis.