Greek civil servants have walked off the job on a 24-hour strike, paralysing the public sector in a protest over ever-deeper austerity measures applied as the government struggles to avoid a catastrophic default.
Air traffic controllers joined the Wednesday strike, grounding all flights to and from Greek airports.
State hospitals were running on emergency staff, while lawyers, school teachers and tax officers also were out.
Public transport workers were holding work stoppages in the morning and evening, and state television and radio pulled news programs off the air.
Demonstrations are planned later in the day in central Athens. Civil servants are protesting plans to suspend about 30,000 staff on partial pay, part of new cutbacks that come on top of salary and pension cuts, as well as repeated waves of tax hikes over the past year and a half.
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Greece relies on a 110 billion euro ($A154 billion) package of international bailout loans to prevent default and to pay salaries and pensions.
But it has slipped on meeting budget targets required to qualify for the funds.
Global markets have been roiled by concerns that a messy Greek default could bring down European banks, drag other troubled eurozone countries into further financial trouble and trigger another global recession.
Venizelos insisted Greece would be able to meet its commitments and that there was no question of a default - but urged his countrymen to pay their taxes and support the government effort to ensure the situation doesn't deteriorate.
The country is suffering through a deep recession, with the economy expected to contract by 5.5 per cent of Gross Domestic Product this year.
Unemployment has spiralled to above 16 per cent as businesses across Greece have closed down.
