Rioting spread across central Athens on Sunday with dozens of buildings engulfed in flames amid broader mass protests as lawmakers were set to cast a key vote on a new round of austerity measures needed to prevent bankruptcy, dpa reported.
Greek riot police clashed with more than 2,000 black-hooded anarchists carrying clubs and petrol bombs on dozens of fronts across the city.
Thick clouds of smoke and tear gas filled the air around parliament, as more than 15 buildings, including shops, banks, cafes and two cinemas were set ablaze.
More than 80 people, among them 30 police officers were reported injured and dozens of arrests were made, police said.
Earlier thousands of protesters earlier marched to parliament. Organizers put the number of marchers at more than 200,000, but police told dpa that the number of demonstrators numbered 55,000.
While most of the protesters were peaceful, dpa reporters saw several hundred of them fighting alongside the anarchists at various locations around the city centre.
Unlike on previous occasions, the anarchists were applauded by other demonstrators as they made their way toward the parliament building in Syntagma Square.
Among those who joined the campaign against Greece accepting a bailout in return for harsh measures were well-known composer Mikis Theodorakis, 86, and veteran leftist politician Manoli Glezos, 89.
Giorgos Makris, a 44-year-old mathematics teacher, said he was not going to back-down and would continue to fight against the harsh new measures, which were widely expected to be approved in a late parliamentary vote.
"I am fighting for my future which they have destroyed by cutting my salary by 20 per cent," he said.
The riots took place as Greek politicians were set to hold a key vote on a new round of austerity measures, with Germany piling pressure on them to finally deliver on their promise to put the country's finances in order.
Parliament was widely expected to approve the measures - along with a bond-swap deal with private creditors allowing Greece to shave off at least 100 billion euros (131 billion dollars) of its 360-billion euro debt - in the vote, scheduled for 2200 GMT.
German Finance Minister Wolfgang Schaeuble said Greeks should be aware of the fact that there was a need for dramatic change.
"That's why now promises are not enough anymore," Schaeuble said in remarks carried by the newspaper Welt am Sonntag.
Greece will default on its debt on March 20 if it fails to secure the 130-billion-euro bailout from the European Union, the European Central Bank and the International Monetary Fund.
The austerity measures include a 22-per-cent cut in the minimum wage, public sector layoffs and pension cuts.
The two biggest parties in the coalition government, the Socialist PASOK and the conservative New Democracy party, have 236 deputies in the 300-member parliament. Only about 13 conservatives and seven Socialists have declared they intend to vote against the legislation.