Greece is braced for a 48-hour general strike across public and private sectors in protest at a proposed new wave of spending cuts.
Protest marches – which regularly end in running battles with police – are planned for the centre of Athens.
The action coincides with a debate in parliament on the austerity measures, with a vote by MPs due on Wednesday.
Greece must back the measures, and the 2013 budget, to receive the next part of a bailout and avoid bankruptcy.
The latest strike starting on Tuesday includes public transport workers, lawyers, air traffic controllers, taxi drivers, journalists and hospital staff.
Some transport and media workers downed tools on Monday as well.
With proposals for a fifth consecutive cut to pensions, an increase in the retirement age and reductions to salaries, benefits and healthcare, the fury among Greece’s population is growing.
Greek ministers say the package should save a total of 13.5 billion euros ($17 billion) by 2016.
Approving the tough reforms and passing the 2013 budget are key to receiving a 31.5 billion-euro installment from the International Monetary Fund and European Union that has been on hold for months.
However, the Democratic Left Party which is the junior member of the three-party governing coalition, is refusing to back the package.
The second biggest coalition party, the socialist Pasok, is also facing a rebellion by some MPs.
Prime Minister Antonis Samaras has tried to reassure the public, who have endured repeated rounds of austerity and a five-year recession.
“These will be the last cuts in wages and pensions,” he said on Sunday.
“We promised to avert the country’s exit from the euro and this is what we are doing. We have given absolute priority to this because if we do not achieve this everything else will be meaningless.”