Thousands of striking Greek teachers have marched in the capital Athens to demand pay rises, while civil servants have gone on a 24-hour strike.
Protesters want more money for the public sector
They want the government to reverse its plans for public spending cuts in the 2007 budget.
The government is already under pressure from primary school teachers, who have been striking for a month.
The 2007 draft budget aims to cut the deficit below the level required by the European Union, to avoid sanctions.
The industrial action comes ahead of Sunday's municipal elections, seen as the first test for the government of Prime Minister Costas Karamanlis after his conservative New Democracy party came to power in 2004.
Education Minister Marietta Giannakou said the government would not back down.
"Certain political groups want civil unrest. They are backing a cause that is fading," she said.
Athens bus and train staff took part in the strike, leading to public transport disruptions.
Government offices and state banks shut down for the day.
The teachers' demonstration was supported by Greece's two main unions, the General Confederation of Greek Workers and Public Servants Union (ADEDY).
After the march, anarchists threw petrol bombs into a Starbucks coffee shop and a far-right publisher's bookstore, causing minor damage but no injuries, the Associated Press news agency reported.
Riot police made minor use of tear gas when a group of anarchists threw stones at them.
Hooded youths also tried to burn a stand of a far-right candidate for mayor of Athens, injuring one man. No-one was arrested.
Government officials claim the protests are in part encouraged by opposition parties in view of Sunday's municipal elections.
The unions insist on pay rises in the public sector and demand the government reverses its plans for spending cuts.
The 2007 draft budget, unveiled last week, envisages cutting the fiscal deficit to 2.4% of gross domestic product to meet euro zone requirements.
The 3% cap aims to ensure the euro is not undermined by over-spending states. Governments face fines if they break the rule.