Greek workers shut schools and forced hospitals to operate with only emergency staff on Wednesday at the start of a 48-hour strike against the latest plans to fire thousands of public sector employees.

Efforts to shrink the 600,000-strong civil service, long seen as wasteful and corrupt, have been resisted by labor unions who say the scheme will only worsen the plight of Greeks enduring a sixth year of recession.

The latest strikes, called by public sector umbrella union ADEDY, comes days before the "troika" of European Union, European Central Bank and International Monetary Fund lenders visits Athens to check on progress made on promised reforms.

More than 9,000 workers, some waving black flags and banners reading "No to firings!" flooded the street in front of parliament in the central Syntagma Square, the focal point of anti-austerity protests.

"We want to tell the government enough is enough," said 54-year-old teacher Vasiliki Angelatou, a mother of two unemployed children who has had her salary more than halved since the crisis began.

"They are firing indiscriminately. We've reached our limits."

Prime Minister Antonis Samaras has promised a population worn down by the worst post-war crisis that economic pain will ease next year once Greece returns to growth.

He has repeatedly branded Greece's efforts to reform as a European "success story" but that is cold comfort to Greeks after three years of austerity measures, plummeting living standards and rising unemployment.

"Where is the success story when our kids are going abroad because there are no jobs?" Angelatou asked.

Turnout at the rally was less than in the past, as Greeks show a growing sense of resignation.

Athens must put a total of 25,000 workers in a so-called "mobility scheme" by the end of the year, to be either transferred to other government jobs or dismissed. It must also meet a target of 15,000 mandatory job cuts in 2013-2014.

The troika has bailed out Greece to the tune of 240 billion euros ($320 billion) but has warned it will stop paying unless Athens pushes forward with reforming a corruption-prone state apparatus where hiring is often driven by political patronage.

Journalists, lawyers, municipal employees and staff at tax and customs offices were among those joining the walkout.

"A long, onerous and painful winter has begun," said ADEDY, which together with private sector union GSEE represents about 2.5 million workers.

The union said: "The truth is that with every troika visit, our national dignity is destroyed. The economy and society are ruined."