A 24-hour general strike is under way in Greece in protest at the nation's austerity measures.
Flights and ferry services have been cancelled, schools, government offices and tourist sites closed, and hospitals are working with reduced staff.
At least 16,000 people have joined protests organised by the main unions in central Athens.
The European Commission is discussing ways of propping up banks in Europe to protect them from the Greek crisis.
Meanwhile, in its latest report on the European economy, the International Monetary Fund (IMF) has warned that economic growth is in danger of petering out and a global recession in the coming year cannot be ruled out.
Global financial markets have been in turmoil over fears that Greece could default on its debt, most of which is held by European banks. In other developments:
On Tuesday, Moody's ratings agency slashed Italy's credit rating from Aa2 to A2, blaming an overall loss in confidence in eurozone governments.
Despite the Italian downgrade, European markets rose sharply as trading opened on Wednesday.
Belgium and France are working on plans to rescue the Franco-Belgian Dexia bank, which is exposed to Greek debt.
German Chancellor Angela Merkel said again that Greece must remain a member of the eurozone.
The general strike is the first since the Greek government announced an emergency property tax and the suspension of 30,000 public sector staff last month.
'Lives ruined'
The government says the stringent austerity measures cannot be avoided if the country is to reduce its deficit of 8.5%, a key requirement in securing a second instalment of bailout cash pledged by the EU.
But the measures are hugely unpopular and have led to a wave of strikes and protests.
Tens of thousands of people have stayed away from work across Greece, including air traffic controllers, tax workers, teachers, hospital staff, public transport workers, police and other emergency workers.
Thousands of people have gathered in central Athens to march towards Syntagma Square and stage a demonstration outside parliament. Protests were also planned for other cities.
Police have fired tear gas at small groups of protesters who were throwing stones.
Critics of the austerity drive say it is deepening the recession, stunting Greece's growth - the economy will shrink 5.5% this year - and stopping Greece from being able to reduce its government debt itself.
Protesters also say they are unfairly bearing the burden of the country's debt.
"This is an opportunity for the Greek people, whether in the public or in the private sector, to fight this, to deny this logic that we must bow our heads all the time to save the country and show patriotism," said 37-year-old protester Dimitris Kizilis.
