Greek police have clashed with protesters in the capital Athens as unions stage a general strike against government austerity measures.
Demonstrators threw petrol bombs and police responded with tear gas as the violence flared outside parliament.
A former minister was chased and beaten by a mob and forced to seek shelter in a building.
The day of action has grounded flights, disrupted public transport and closed schools across the country.
It is the seventh general strike this year following tough reforms needed to receive a 110bn euro (£84bn) bail-out from international organisations.
Police said about 15,000 people were taking part in marches in Athens.
Protesters started fires around luxury hotels in Syntagma Square, outside parliament, and cars were set ablaze. Riot police fired several rounds of tear gas in response.
The BBC's Malcolm Brabant in Athens says the scenes are some of the ugliest in a year of protests marking the country's economic crisis.
He says a lynch mob atmosphere developed as former conservative minister Kostis Hatzidakis emerged from parliament and was chased by dozens of protesters.
The opposition MP was pictured surrounded by a mob and with blood pouring from a head wound. Mr Hatzidakis's office said he was unable to reach hospital because of the crowds.
Witnesses said demonstrators shouted at him: "Thieves! Shame on you!"
Police said at least 10 people had been detained and three had been injured.
With public transport at a standstill, major roads connecting the centre of Athens were jammed as motorists struggled to get to and from work.
Journalists were also on strike, affecting news bulletins on TV and radio.
Teacher Anastasia Antonopoulou, 50, travelled from the Ionian island of Zakynthos to join thousands marching through Athens on Wednesday.
"I can't sit on the sofa and watch my country go down. I'm here to shout and struggle," she said.
"Many of my students' parents are jobless."
On Tuesday, the Greek parliament voted through key economic reforms stipulated by the International Monetary Fund (IMF) and European Union, which are funding the bail-out.
The new legislation will cap the salaries of workers in state-run companies such as the public transport networks.
In the private sector, employers will no longer have to abide by union-negotiated agreements and can set their own wages.
Prime Minister George Papandreou said the measures were designed to keep struggling companies afloat.
But union leaders have condemned the moves.
"We need to send the government a message that we will not accept measures that lead us only to poverty and unemployment," Ilias Iliopoulos, general secretary at the civil servants' union Adedy, told Reuters news agency.
Our correspondent says opposition groups are angry with the government for taking just 10 hours to debate such major changes to employment law.
However, as a result Greece is now more likely to receive its fourth instalment of financial aid due in the New Year, he adds.
Wednesday's strike is part of a European day of action against economic reforms.
Workers have been rallying against austerity measures in countries including Spain and Belgium, ahead of a summit of EU leaders in Brussels on Thursday and Friday.