ATHENS—Tens of thousands of Greeks took to the streets Wednesday as much of the country went on a 24-hour strike against government austerity measures.

A small group of youths threw Molotov cocktails at police, who responded with tear gas. However, the 20,000 people who filed through downtown Athens—a relatively large crowd for a Greek strike—mostly limited themselves to chanting anti-government slogans.

Public- and private-sector unions called the strike to protest a range of measures aimed at reducing Greece's budget deficit. The government has announced a freeze on civil-service wages, cuts in public-sector entitlements and the closing of tax loopholes for certain professions, including some civil servants. It has also announced a fuel-tax increase.

"There is an all-out war against public servants, those who earn the least," said Spyros Papaspyros president of ADEDY, an umbrella union for public-sector workers. "We will fight to keep the little we have. The government and the EU must understand the crisis must be paid by the rich."

The government moves are aimed at reducing Greece's budget deficit, which at about 13% of gross domestic product last year was well over the EU's 3% limit. This has raised the interest rate Greece has to pay to borrow money. Brussels has ordered Greece to bring the deficit to within the EU limit by 2012.