Greek prime minister George Papandreou will tomorrow strive to stem an outbreak of unrest in his party over the social cost of a new bailout after data laid bare the depth of the country's economic crisis.

Discontent in the ruling Socialist party (Pasok) could yet spill over into a full-scale parliamentary rebellion and tens of thousands are protesting regularly in central Athens against waves of austerity demanded by the European Union and IMF, as well as corruption and state mismanagement.

But Mr Papandreou told his Pasok's political council today that the extra austerity included in a new 2011-2015 fiscal plan, which will be submitted to parliament this month, is necessary to stem the crisis.

"The time has come to move with greater boldness ... always in a democratic way but with determination and unity in the great changes the country needs," he said. "This means that we must proceed responsibly in finishing and passing the medium-term plan."

Unemployment climbed to 16.2 per cent in March, the highest in the euro zone after Spain, while industrial production tumbled 11.0 per cent year-on-year as Greece suffers its third year of recession, major public spending cuts and higher taxes.

Labour minister Louka Katseli said Pasok deputies wanted to know whether the sacrifices Greeks have made under the original 110 billion euro bailout, agreed with the EU and IMF a year ago, were bearing any fruit. "The deputies are demanding that the burden should be shifted to those who can withstand it better," she told Mega TV.

Until now dissent has been muted among the ruling Socialists. But Greeks have staged nightly protests for a fortnight in the capital's Syntagma Square to hurl abuse at the parliament building, with numbers hitting over 80,000 on Sunday.

Many Pasok backbench members of parliament appear to be taking fright.

Reuters