Clashes broke out Wednesday between police and protesters trying to surround the Greek parliament, and police fired tear gas to disperse the crowd.
Workers in Greece are in the second day of a 48-hour general strike, and the country is all but shut down by the protest action, aimed against a new round of national austerity reforms.
Wednesday's clashes took place as lawmakers considered Prime Minister George Papandreou's plan to raise taxes, cut government spending and sell state assets.
A prominent opposition conservative, Elsa Papadimitriou, said she is breaking with her party and will vote for the austerity plan when it comes up for a parliament vote later Wednesday.
The first day of the general strike Tuesday resulted in a demonstration in Athens by about 20,000 people. Initially peaceful, the protest turned violent. At least 4,000 police officers armed with stun guns, tear gas and batons fought protesters who hurled rocks and firebombs.
At least 14 protesters were arrested, and more than 20 people suffered injuries.
Greece must adopt the austerity plan by Thursday, if it is receive $17 billion in international aid and also avoid default on loans received last year as part of a $156 billion bailout plan.
Many protesters feel the $40 billion austerity plan imposes harsh penalties on workers and pensioners, while sparing the wealthy.
Transportation, schools and other services were closed Tuesday, as well as many private businesses. Hundreds of flights were canceled or rescheduled as air traffic controllers walked off the job. The air traffic controllers' union said airports would be closed for several hours again Wednesday.
Christine Lagarde, the new head of the International Monetary Fund, called on Mr. Papandreou's opponents to support the austerity package, “in the spirit of national unity.”
EU officials have warned that Greece has no choice but to adopt the austerity plan. They add that any default on Greece's loans would be a calamity for the 17 countries that use the common euro currency and the broader world economy.
