Thousands of Greeks have rallied against deficit-cutting measures during a national public sector strike.
Flights have been grounded, many schools are closed and hospitals are operating an emergency-only service.
The prime minister, who wants to freeze pay, gather more taxes and reform pensions, insisted that the proposals would be fully implemented.
EU leaders will discuss Greece’s difficulties on Thursday amid concern the crisis could threaten the euro.
European finance ministers are also due to hold a teleconference on Wednesday to talk about the issue.
Despite heavy rain, there have been rallies across Greece throughout the day, with thousands of striking workers and pensioners gathering in the capital, Athens.
Several thousand people were also reported to have protested in Greece’s second city, Thessaloniki.
