Greek police deployed in strength Wednesday to prevent thousands of anti-austerity protesters from blockading Parliament, where the struggling government will launch a debate on new unpopular cutbacks needed to secure international rescue loans.

As a 24-hour general strike got under way, a large part of central Athens was closed to all traffic and pedestrians as police mounted a huge security operation to allow lawmakers access to Parliament by car.

Some 5,000 officers, including hundreds of riot and motorcycle police, were on duty, using parked buses and crowd barriers to prevent protesters from encircling the building.

At least 11,000 people gathered peacefully in Syntagma Square outside Parliament, according to police, while another union demonstration was expected later Wednesday.

"Resign, resign," the crowd chanted outside Parliament. The protesters included both young and old, and many brought their children, hoisting them onto their shoulders to shield them from the crush.

Such marches have often turned violent in the past, and three clerks died when rioters torched their bank during a mass demonstration in Athens last May. But no violence was reported Wednesday.

"What can we do? We have to fight, for our children and for us," said Dimitra Nteli, a nurse at a state hospital who was at the protest with her daughter. "After 25 years of work I earn 1,100 euros a month. Now that will drop to 900. How can we live on that?"

Her daughter, Christina, 26, said the situation in Greece had led her to seek a university place abroad. She is leaving to study conflict resolution in the United Kingdom.

"I have no job here. There are no prospects," she said

Police spokesman Athanassios Kokalakis said 10 protesters were briefly detained for trying to prevent lawmakers from reaching Parliament. About a hundred people booed and heckled as cars carrying Prime Minister George Papandreou and President Karolos Papoulias swept past.

Meanwhile, a general strike by unions crippled public services across the country.

It left state hospitals running on emergency staff, disrupted port traffic and public transport, and forced radio and television news programs off the air. Journalists' unions later called off the strike to cover developments in Athens.

Flights, however, were operating normally after the air traffic controllers' union called off their participation in the strike.

"They keep asking us to give more," said Ilias Iliopoulos, general secretary of the civil servants' union ADEDY. "Now, again, they will cut our salaries and bonuses, from the little that we have left."

The government needs to pass a new 2012-2015 austerity program worth 28 billion euros ($40.5 billion) this month — or face being cut off from a 110 billion euro package of rescue loans from European countries and the International Monetary Fund.

To meet their commitments, Papandreou's Socialists' abandoned a pledge not to impose new taxes and have drawn up a four-year privatization program worth 50 billion euros ($72 billion) — further fueling protests against austerity by public utility employees and other affected groups.

Some of the lawmakers from the governing party have publicly criticized the new cuts. One of them defected on Tuesday, reducing Papandreou's parliamentary majority to five in the 300-seat legislature. Another Socialist lawmaker said he will vote against the bill, which is set for final approval by early next month.

Facing an open revolt from within his own party and a refusal by the main opposition conservatives to back the new austerity bills despite EU pressure for cross-party support, Papandreou was to meet with the country's president later in the day.

With its credit rating deep in junk status, Greece is being kept afloat by the EU and IMF bailout, but will need additional support to cover financing gaps next year as high interest rates will prevent it from tapping the bond market next year, contrary to what the original bailout agreement had predicted.

On Monday night, Standard & Poor's slashed Greece's rating from B to CCC, dropping it to the very bottom of the 131 states that have a sovereign debt rating. That suggests Greece's creditors are less likely to get their money back than those of Pakistan, Ecuador or Jamaica.

It's an astonishing low for Greece. As recently as January 2009, the country still had a stellar A rating despite a hefty debt burden.

Punishing austerity measures have seen the Socialists' popularity plummet in recent weeks. A weekend opinion poll gave the main opposition conservatives a four-point lead over their Socialist rivals, the first time the party has been ahead in surveys since 2009. The next general election is scheduled for October 2013.