Greek demonstrators stormed the country's Labor Ministry and confronted its chief on Tuesday in protest at moves to restrict the right to strike, a condition set by international creditors in exchange for bailout funds.
Athens is set to introduce legislation which could limit the frequency of strikes in the country, infuriating labor unions which regard industrial action as sacrosanct.
Using crowbars, about 500 demonstrators with Greek Communist-affiliated group PAME prised open metal shutters of the labor ministry in central Athens, racing up to the eighth floor of the building where about 50 of them came face to face with Labour Minister Effie Achtsioglou.
The 32-year old minister is a staunch leftist in the government of Prime Minister Alexis Tsipras.
Visibly disturbed, Achtsioglou was silent as demonstrators shouted "shame on you" over legislation due to go to parliament this week.
"Take it back," they shouted. "I will not take it back," she responded.
Her office was undamaged, but a Reuters witness saw two to three desks in the corridor leading to her office damaged or overturned.
Earlier, about 500 protesters had rallied outside the labor ministry, putting up a banner reading "Ministry of EU and IMF!" and chanting "We won't yield to plutocracy!"
The European Union and International Monetary Fund have bailed Greece out from becoming bankrupt due to oppressive debt, but demanded severe austerity in exchange. Part of that has been changes to the labor law.
More protesters arrived as a group unfurled a huge banner that read "Hands off strikes, it's a labor right!," hanging it from the roof of the ministry on a busy street in central Athens.
Greece's leftist-led government was due to submit a bill with bailout-mandated reforms to parliament on Tuesday. The government has agreed to increase the quorum for unions to vote on a strike.
Lawmakers are expected to vote on the reforms before a meeting of euro zone finance ministers on Jan 22, which will assess the country's bailout progress as part of a review by its lenders.