Employees at state companies earmarked for privatisation began a 24-hour strike and thousands of civil servants staged a walkout from mid-morning in protest against a coming wave of additional austerity cuts.

Prime Minister George Papandreou has called a cabinet meeting for 2:00 pm (1100 GMT) to finalise the details of a four-year economic recovery plan designed to economise more than 28 billion euros ($41 billion) by 2015.

Greece received a 110-billion-euro ($160 billion) bailout last year, but with state debts having ballooned to some 350 billion euros and a deeper-than-expected recession lessening the impact of sharp spending cuts, a second bailout is considered unavoidable.

But the EU and the IMF, which led last year's rescue, have demanded proof of reforms in Athens before approving further aid.

Time is running short, as Greece has warned it will be unable to pay next month's bills without a loan instalment of 12 billion euros earmarked under the original EU-IMF rescue package.

The government hopes to push the reform package through parliament, where it holds a six-seat majority, by the end of June.

Ministers enlisted to brief the ruling party's lawmakers on the package received a dressing-down on Tuesday, with many internal critics arguing that the recovery recipe mandated by Greece's creditors is ill-thought.

The plan was designed to help Athens regain access to borrowing markets but investors remain unconvinced and credit rates have risen instead of falling.

Faced with domestic opposition and resistance from unions, the government had dawdled for more than three months on a 50-billion-euro privatisation drive announced in February.

The head of the ministerial Eurogroup, Luxembourg Prime Minister Jean-Claude Juncker, on Wednesday called for a "re-invigoration of fiscal and broader structural reforms."

"We acknowledged the significant progress achieved so far by the Greek authorities, in particular as regards fiscal consolidation, although a reinvigoration of fiscal and broader structural reforms remains necessary," Juncker said.

He was speaking after Greece's main opposition leader Antonis Samaras, who is calling for a renegotiation of the country's rescue deal, met with senior EU officials in Brussels.

"The adjustment of the Greek economy can only succeed when all relevant political parties subscribe to the objectives and main parameters of the programme," Juncker noted.

Tens of thousands of Greeks have been gathering opposite parliament daily over the last two weeks to protest against the austerity policies which are seen to have pushed the economy into a deeper hole.