Greece was hit Thursday by its fourth general strike of the year against harsh austerity measures aimed at easing the cash-strapped company's financial problems.
The strike was the first since demonstrations against government policies turned deadly on May 5 when three people were killed in a bank fire.
Thousands of anti-riot police were deployed across Athens as more than 20,000 protesters marched in front of the parliament denouncing cutbacks on salaries and pensions, tax hikes and changes in the pension system that raise the retirement age.
"Thieves get out," angry citizens chanted as minor clashes with police occurred in front of the parliament building and the Unknown Soldier's Tomb.
Police earlier apprehended 20 people at Exarchia, a central Athens district which for years has been regarded as a kind of ghetto created by anarchists.
A wide majority of Greeks denounce the violence caused by hooded young men who damage property, endanger lives and mar peaceful rallies, but are not willing to stop the protests.
"We cannot give in to such changes that strangle our families. We cannot survive with such small wages and high taxes. After all we are not to blame.
Corrupted thieves should pay," said Thanasis Stamou, a 35- old civil servant who took part in the demonstration.
Similar rallies were held in other Greek cities.
The Greek government promoted the austerity measures as absolutely necessary to tackle an acute debt crisis and create a better future for all citizens.
The reforms were implemented under the pressure of European partners who feared the prospect of a domino effect in Europe stemming from the Greek crisis.
Over the past week, Greece received the first package of loans from the European Union and the International Monetary Fund to meet imminent financing obligations.
Without the aid of tens of millions of euros, Greece faced even bankruptcy.
Ordinary Greeks recognize that something should be done, but they do not believe that the solution agreed on by the Greek government, EU and IMF was the best possible.
"Arrest tax dodgers and ask banks to pay," was written in one of the banners raised by protesters on Thursday, as a small group close to the Greek Communist Party blockaded the entrance of the Ministry of Labor in the center of Athens.
Across Greece hospitals, schools and other public organizations operated with emergency personnel, while disruptions were reported in public transport, as buses, subway, railway services and ships were not operating.
The picture was slightly better in airports, as most flights were not disrupted because air traffic controllers stayed on the job.
Greek hoteliers reported thousands of cancellations of bookings from abroad this month due to the violence.
Greece is trying to avoid more damage to its tourism industry, which is a significant source of revenue for the national economy.
Thursday's mobilization was seen as a new test of strength for the government and unions, local political analysts said. While both sides still retain their positions, commentators noted that if reactions get stronger, the government will be under pressure to make adjustments.
That prospect would not please international lenders who expect quick results from the implementation of the austerity program.
The most probable development would be the fading of protests this summer and a new wave of protests in the autumn, Greek media predicted.