Police clashed with stone-throwing youths in Athens on Thursday as tens of thousands protested draconian cutbacks aimed at pulling Greece out of a debt crisis shaking the euro zone.

About 50 black-hooded youths hurled sticks and pieces of marble broken from the steps of the Bank of Greece at police, who responded with several rounds of tear gas.

The youths threw petrol bombs, smashed shop windows and set garbage containers on fire, but the level of violence was much lower than during 2008 riots that paralyzed the city for weeks after the police killing of a teenager.

Waving leftist and anarchist flags, the hooded youths chanted Let parliament burn.

Two police officers were wounded during the clashes and 16 protesters detained, a government official said.

In otherwise largely peaceful protests, about 23,000 people marched through Athens to protest cuts in civil servants' income, tax hikes, a pension freeze and plans to raise the retirement age. Public and private sector workers staged a nationwide strike.

Most Greeks believe that, despite the protests, the cash-strapped socialist government will press ahead with a plan agreed last week after months of wrangling with the EU and intense pressure from financial markets.

But the 4.8 billion euro ($6.5 billion) package of cutbacks is largely viewed as hitting the wrong people in a country with widespread corruption and tax evasion.

The measures are unfair ... we cannot make it, we have children, families. We need to find the money to support them, said 60-year old health sector worker Odysseas Panagopoulos. Banks and rich people should pay for this crisis.

The strike, organized by unions representing half of the country's 5 million strong workforce, grounded flights, docked ships, shut schools and hospitals and halted public transport in the second nationwide walkout in a fortnight.

Many archaeological sites and museums were closed to visitors and the publication of GDP and unemployment data was postponed.

There was no news on television and radio as journalists went on strike, and bank employees, firemen, tax collectors and even some police officers were also among those marching.

WHERE IS THE MONEY?

Athens' streets echoed with loud-speakers blaring slogans calling for the rich to pay for a severe debt crisis. No sacrifice for the rich! protesters chanted, beating drums and holding banners reading: Where did the money go?

The level of participation in the strike and protests will be watched closely outside Greece. EU policymakers, rating agencies and financial markets welcomed the latest measures but want to see them implemented quickly and smoothly.

The general strike takes place as EU policymakers are discussing ways to help the euro zone weakling.

Officials and unions gave widely diverging estimates of participation in the strikes. Interior ministry officials said about 15 percent of civil servants had walked out, while their union put the level at over 65 percent.

Participation in the marches through Athens was slightly higher than in the previous nationwide strike on February 24 but not huge by Greek standards and much smaller than a 100,000-strong march against similar measures in the Irish capital last year.

People understand we are going through difficult times, a senior government official said.

Last week's package, aimed at reassuring markets that Athens can handle a 300 billion euro debt mountain, came just 5 months after the socialists won an election on a promise to help the poor deal with Greece's first recession in 16 years.

This government deceived us, said Zaharoula Toulia, a 57-year-old pensioner who lives on 800 euros a month and voted for the socialists. They said there was money. Where is it?

The government blames the last administration, accusing it of concealing the extent of Greece's debt problem.

Groups from taxi drivers to refuse collectors have stepped up protests in recent weeks while unions are preparing further action in April and May.

(Additional reporting by Deborah Kyvrikosaios; Writing by Ingrid Melander; Editing by Dominic Evans)