Demonstrations in Athens have highlighted the opposition to the Greek government's controversial austerity bill. One peaceful rally continued as two groups of anarchists clashed with police.
The bill being debated in parliament is ahead of a vote on Sunday night for measures required by Greece's creditors before a third, international bailout is paid over. The measures will increase social security and pension contributions and raise taxes for most people.
There have been rallies all week ahead of the vote.
A peaceful rally was called Sunday by Greece's biggest unions. Most of the people who turned up were reported to be members of the Communist Party.
Two groups of anarchists also turned up. One mixed with the union rally, another split off and moved towards the Syntagma Square in front of the parliament building.
Firebombs, chairs and wooden planks were thrown at police who responded with stun grenades and tear gas. Anarchists were also accused of targeting individuals within the crowd.
Greece has been tense for some days amid a general strike that has paralyzed much of the public transport across the country.
Thousands of people also took to the streets in the Greek city of Thessaloniki to show their anger against the proposed tax and pensions overhaul.
On Sunday, Greek lawmakers began a final day of debate over the new and tough package of reforms that the parliament is to vote on ahead of a crunch meeting of the country's eurozone creditors.
The austerity measures, to the tune of 5.4 billion euros ($6.2 billion), are part of a package of painful reforms that the European Union and international creditors are demanding in return for an 86 billion-euro bailout agreed to last July in a bid to pull Greece out of its debt crisis.
Growth forecasts published by the European Commission last week estimated that Greece's public debt will rise to 182.8 percent of GDP this year - a record within the eurozone.
Prime Minister Alexis Tsipras of the leftist Syriza party brought forward the vote on the reforms in the hope that a meeting of eurozone finance ministers on Monday can move on from approving the reforms to a discussion on debt relief for the country.
The International Monetary Fund (IMF) believes that the mammoth debt payments currently made by Greece will be unsustainable in the long term.
Tsipras defends the bill
The reforms under debate in the Greek parliament would cut the country's highest pension payouts, merge several pension funds, increase contributions and hike taxes on medium and high incomes.
The pension cuts are to save 1.8 billion euros, while the tax reforms are to bring in another 1.8 billion. The parliament will decide later on raising indirect taxes to collect the same sum again.
Tsipras on Friday defended the measures, saying they would spare the poorest.
shs/jm (AFP, AP, dpa)