Scuffles broke out and police used teargas on Greek workers that went on a general strike and rallied on Thursday to protest against new pension reforms imposed on the Greek government by the country's creditors.
About 50,000 Greeks marched towards parliament in Athens, demanding an end to austerity. Youths hurled stones and petrol bombs at police, who responded with teargas and stun grenades.
The city of Athens was paralysed as public transportation employees participated in the strike organised by Greece's main labour unions, GSEE and ADEDY. Ferry journeys and domestic flights were also cancelled due to the strike.
Greeks took to the streets for the second time since Prime Minister Alexis Tsipras came to power last year promising an end to austerity but accepted demands from international creditors for a reform under a bailout package while the country was in danger of being expelled from the eurozone.
Protests are also expected to take place outside of the Greek parliament later in the day.
"They should be strung up here, in Syntagma Square," said pensioner Nikos Ghinis. "I'm getting 740 euros ($826.21) a month for 40 years of work." I'm demonstrating here for my children and grandchildren, he told Reuters.
The general strike came after the heads of the European Union and International Monetary Fund arrived in Athens to meet with the Greek government in order to discuss the progress of the bailout.
The Greek government hopes for debt relief after the creditors assess Greece’s progress.
The new reforms to be imposed include pension spending cuts of 1 percent of GDP or 1.8 billion euros this year while social security contributions will be increased.
The angry backlash is putting pressure on Prime Minister Alexis Tsipras who is stuck between either pushing the reforms through to appease international creditors, or attracting the wrath of thousands of Greeks.
The unions say that the new reforms will worsen unemployment even more while the unemployment rate is currently 25 percent and will force workers, mainly the self-employed, into tax evasion as it links social security contributions to declared income.
"We will reach a stage where we won't be able to make ends meet unless we steal from the state," said demonstrator George Stathopoulos, 70.
"We cannot live, we cannot survive with what the government is asking from us," said farmer Socratis Aleiftiras, among the thousands of farmers who have blocked roads across the country for the past two weeks.