Public transport was disrupted across Greece on Wednesday as unions staged a 24-hour strike to protest the government's austerity measures, dpa reported.
Ferries remained docked across the country, rail services were halted and hospitals were functioning with skeletal staff.
The unions were planning to hold a rally through the centre of Athens later in the day.
The demonstrations on Labour Day are against the government's plan to cut 15,000 public sector jobs by the end of 2014.
The measures are demanded by Greece's international creditors in return for releasing an 8.8-billion-euro (11.5-billion-dollar) tranche from the rescue package that has kept the government solvent.
This year, however, Greece marks Labour Day on May 7 - which will be a public holiday - to coincide with the Greek Orthodox Easter religious holiday.