Public services were shut down across Greece on Wednesday in a nationwide strike over an austerity drive by the government, which is struggling to avert a default.
More than 400 domestic and international flights were cancelled, schools have been closed and hospitals are running on emergency staff.
Later in the day, state workers, students and pensioners will march on Athens's central Syntagma Square and protest outside parliament.
The strike comes after the government announced an emergency property tax and the suspension of 30,000 public sector staff. A day earlier, protesters blocked all access to several key government ministries while a nationwide general strike is also planned for October 19.
On Monday, Eurozone finance ministers delayed making a decision on giving Greece its next installment of bailout cash, sending European shares down sharply. The move came after Greece said it would not meet this year's deficit cutting plan.
The European Commission is meeting later to discuss coordination on propping up banks in Europe.
