Greek anti-austerity protesters stormed the office of the labour minister on Wednesday and clashed with police after 30 demonstrators were arrested.
The scuffles erupted after police detained members of the Communist-affiliated PAME group who had forced their way into the ministry and occupied Labour Minister Yannis Vroutsis's office for about two hours.
Police fired teargas and used batons to disperse roughly 300 demonstrators who rallied outside the ministry in solidarity, with banners reading "No to cuts!" and "Take to the streets!"
Greece has seen a surge in protests - many of which have turned violent - since imposing tough austerity measures demanded by its European Union and International Monetary Fund lenders as the price for bailout funds to stave off bankruptcy.
Last week, the government ended a nine-day transport strike by threatening metro workers with arrests if they failed to return to work.
Transport unions and electricity workers plan more anti-austerity strikes on Thursday despite government warnings that it has little patience for labour action that further burdens austerity-hit Greeks.
"Violence in any form must be condemned," government spokesman Simos Kedikoglou said in a statement condemning the occupation of the labour minister's office. "The government will not put up with this kind of incident."
Police said two protesters were slightly injured in Wednesday's clashes.
Protesters chanted, "We are not clients, we are workers" and said they were angered by comments made by Vroutsis on Tuesday when he said Greece's social security system was founded on clientilism.
(Reporting by Yiorgos Karahalis and John Kolesidis; Editing by Rosalind Russell)