Millions of Greeks took part in a 24-hour nationwide strike on Wednesday against planned pension reforms, grounding flights, confining ships to port and closing schools, ministries and banks.
Thousands marched through central Athens, beating drums and chanting slogans such as "The bill is a fraud", to protest against reforms which they say will hurt benefits.
Police used teargas to disperse a small group of protesters who hurled a petrol bomb outside parliament.
"The participation in the strike is total. We are talking about millions," said Spyros Papaspyros, president of the civil servants umbrella union ADEDY, one of the strike organisers. "The government must not underestimate this public outrage."
ADEDY and its private sector sister GSEE represent about 2.5 million members. A government official who requested anonymity said participation in the public sector was about 31 per cent. He did not give an estimate for the overall strike.
Legislation that aims to overhaul the ailing social security system, which experts say is destined to collapse in 15 years if left unchanged, goes to parliament for a final vote on Thursday.
"We will not weigh the political cost when called to come through with the pension reform we promised the Greek people," Labour Minister Fani Palli Petralia told parliament. "We cannot postpone or push (it) back – the problem is here."
The government, re-elected in September on pledges not to curtail pension rights, needs the backing of all its 151 deputies in the 300-seat assembly to pass the bill.
Unions say Prime Minister Costas Karamanlis has not kept his word and that reforms limit workers' benefits without improving the system.
"Today we dump the bill in the landfill," GSSE Vice-President Alekos Kalyvis told a mass rally in central Athens. "Mr. Karamanlis's nose is growing like Pinocchio's. He has gone back on all that he pledged before the elections."
Protests in recent weeks have caused blackouts, left mountains of rubbish in the street, disrupted transport and services, and halted trading on financial markets for days.
At least 150 flights could be cancelled on Wednesday and many more delayed because air traffic controllers were taking part in the strike.
Monuments and the Athens Acropolis closed early because of a walkout by guards planned for noon. Schools, ministries and banks were closed.
"This bill will hurt all of us but especially women. We want it withdrawn," said student Irini Koubi, 21, beating a drum while marching with about 10,000 others to parliament.
About 50 self-proclaimed anarchists broke from the main march and hurled a petrol bomb at police, who answered with teargas outside parliament. The anarchists dispersed but not before smashing the windows of three banks and setting fire to garbage cans, police said.
The reform bill affects mostly women, and especially working mothers, who until now could retire earlier and in some cases with full benefits. It merges scores of funds into just 13, offers incentives for workers to stay at work longer and cuts many special pensions.
Greece is one of several European Union countries facing a pension crisis due to an ageing population and has been urged by Brussels to revamp a fragmented, wasteful and mismanaged social security system urgently.
France and Italy are also facing labour and opposition party reaction to efforts to increase retirement ages and trim benefits as part of overhauling their own pension systems.
Experts say that if the Greek system is left unchanged, the pension funds actuarial deficits could reach €400 billion (Dh2.245 trillion), almost twice the country's GDP. (Reuters)
Millions strike in Greece over pensions