The Greek parliament is set to vote on an austerity package to prevent it defaulting on its debts.
The 28bn euro package is expected to be approved by parliament by a narrow margin, as nationwide strikes and rioting continue.
Violent protests erupted earlier outside parliament when protesters tried to stop MPs from entering.
Anti-cuts protesters in Syntagma Square have set up roadblocks and attempted to ring the parliament building to prevent deputies from entering.
George Papandreou, the Greek prime minister, says his austerity plan is the only viale way to get his country back on its feet.
The vote will cover the first part of the austerity package, focusing on raising taxes and introducing public spending cuts. A second vote on Thursday is due to facilitate a change in law allowing the package to be put in place.
Greece needs to approve these austerity measures to secure the next instalment of the 110bn euro bail-out package being supplied by the EU and IMF.
If passes, details will be finalised of a second bail-out, worth an estimated 120bn euros and designed to help Greece pay its debts until the end of 2014.
The governor of Greece's central bank, George Provopoulos, said a 'no' vote would be "suicide" for the country.