Greek trade unions planned a protest Sunday ahead of a parliament vote on a bill that would spur unprecedented public sector job cuts to meet conditions set by Athens' creditors for billions in bailout loans.
Parliament began debating the legislation - which provides for the dismissal of 15,000 civil servants by 2014, including 4,000 this year - in the morning and a vote was due at midnight (2100 GMT).
Civil service trade confederation Adedy called the demonstration in front of parliament to protest against "those politicians who are dismantling the public service and destroying the welfare state."
Private union GSEE said the bill would only worsen Greece's dire unemployment rate, which currently stands at 27 percent.
Greece's conservative-led coalition has 167 deputies in the 300-seat parliament, more than enough required to pass the bill.
Slashing an unwieldy public service is a condition set by Greece's so-called "troika" of creditors - the International Monetary Fund, European Union and European Central Bank - to unlock loans 8.8 billion euros ($11.4 billion).
The EU and the IMF have committed a total of 240 billion euros in rescue loans since 2010, with the heavily-indebted country obliged to pursue austerity measures in exchange for the international aid it needs to avoid bankruptcy.
The new law will speed dismissal procedures, which previously made it nearly impossible to sack civil servants and saw the public sector swell over the years as every new administration brought in its own people.
The new law also extends weekly working hours for teachers, opens a number of professions to competition and reduces a controversial property tax by 15 percent.