A strike by civil servants brought Greece to a halt as European Union ministers held talks on the debt crisis threatening a growing number of euro countries.
The EU talks with European Central Bank President Jean-Claude Trichet in Brussels heightened speculation that a bailout deal is close.
But in a new sign of the euro zone's problems, Portugal's Prime Minister Jose Socrates said his country also faces a fight to get its finances in order.
The strike in Greece closed government offices, schools and colleges while hospitals only dealt with emergencies.
Flights over Greece were suspended as air traffic controllers joined the protest and rail services were also disrupted.
Around 10,000 people took part in an anti-austerity demonstration in Athens and 3,000 in the second city of Thessaloniki.
Protesters waved banners proclaiming: 'The plutocracy should pay for the crisis,' and specifically targeted 'bankers, shipowners and big business'.
Since the Socialist government revealed last year that the country's finances were in much worse shape than had been thought, markets have punished Greece, doubting the government's will to take decisive action.
Greek Prime Minister George Papandreou has asked civil servants to accept bonus cuts as an example to the rest of the country.
EU leaders are to discuss the Greece crisis at a summit tomorrow in Brussels.
'We are ready to take any necessary measure in order to make sure that the goal of cutting our deficit by 4% in 2010 to 8.7% of our GDP is achieved', Mr Papandreou said after meeting French President Nicolas Sarkozy.
Greece is trying to reduce expenditure and raise revenue to narrow its 12.7% deficit, which is more than four times the permitted euro zone limit as a percentage of gross domestic product.
The Greek crisis has driven up borrowing costs for governments across Europe, with pressure mounting on a number of other indebted euro zone governments, and sent the euro sliding against the dollar.
So sensitive are the markets that the news Mr Trichet was leaving a central bankers' meeting in Sydney early to attend the EU summit was enough to bolster speculation that a deal was in the works.
That eased worries over Europe's debt troubles and brought most markets higher following a rally on Wall Street.
An official from the party of German Chancellor Angela Merkel has indicated that preparations are under way in Berlin for a support plan.
Elsewhere, Portugal's government has confirmed that it is confronting its own debt crisis.
Speaking before a crisis debate in parliament, Prime Minister Socrates said his planned budget was crucial to the country's credibility and stability, warning that 'the road will be difficult and demanding'.
The government has said it intends to reduce the public deficit by 1% to 8.3% in 2010.
By the end of this month it must present a financial stability and economic growth programme to the European Commission.
