Greece is in the grip of a new 24-hour general strike on Wednesday, as the country's largest unions of public and private sector workers ADEDY and GSEE mark Labor Day with anti-austerity rallies in central Athens and other major cities.

Thousands of people took to the streets denouncing the tough economic policies imposed over the past three years in return for international bailout aid to cope with the Greek debt crisis.

Even though Wednesday is not a public holiday in Greece this year, as the government decided t move the May Day celebrations to May 7, after the Orthodox Easter, public services, including hospitals and transport, are disrupted and stores closed.

Hospitals operate on emergency staff, while ferries remain docked at ports nationwide and buses, the subway and inter-city trains services are disrupted by work stoppages.

"No to modern slavery, no more austerity, life with dignity for all," shouted protesters outside the parliament on Wednesday, just three days after deputies ratified the latest set of spending cuts, tax hikes and reforms requested by European Union and International Monetary Fund creditors to unlock about 9 billion euros (11.9 billion US dollars) of rescue loans this month.

On Monday, eurozone officials approved the release of the first installment of 2.8 billion euros.

However, trade unionists who have organized a series of similar protests since 2010 and demonstrators marching to Syntagma square on May Day called for an immediate end to the austerity measures which have led to record high unemployment rates and recession, now in its sixth year.

Greece's coalition government and foreign auditors who have been keeping the country afloat under deals clinched since May 2010 argue that the painful stability and reform program is absolutely necessary and the only way to solve chronic malfunctions, reduce deficits and boost growth to overcome the crisis. (1 euro = 1.32 US dollars)