The leaders of Greece's three-party government have once again failed to agree on a package of spending cuts worth around €11.5bn.
It has renewed fears the country will default on its massive debt.
The coalition has been trying for weeks to secure a deal on pension and wage cuts.
Agreement is viewed as essential if Greece is to continue to secure billions of euros of bailout funds from the IMF and European Union.
Socialist Party leader Evangelos Venizelos said the government could not exceed the people's limits of endurance, in particular across-the-board reductions in pensions and cuts in disability benefits.
Greek Prime Minister Antonis Samaras is due to meet European Central Bank President Mario Draghi in Frankfurt on Tuesday, before the talks on spending cuts resume in Athens on Wednesday.
If the leaders fail to secure a deal, the EU and IMF could withhold bailout funds and Greece would inevitably default.
In the fifth year of a deep recession, Greece has seen its economy shrink by about 20% and the unemployment rate soar to 24.4% in June.
