Greek trade unions have begun the first general strike since the country’s conservative-led coalition government came to power in June.
Wednesday’s 24-hour walkout is to protest at new planned spending cuts of more than 11.5 billion euros ($15 billion).
The savings are a pre-condition to Greece receiving its next tranche of bailout funds, without which the country could face bankruptcy in weeks.
Large anti-austerity demonstrations are also planned.
Greece needs the next 31 billion-euro installment of its international bailout, but with record unemployment and a third of Greeks pushed below the poverty line, there is strong resistance to further cuts.
The government of conservative Prime Minister Antonis Samaras is also proposing to slash pensions and raise the retirement age to 67.
Workers from a diverse range of sectors are taking part in the strike, from doctors to air traffic controllers.
It was called by the country’s two biggest unions, which between them represent half the workforce.
A survey conducted by the MRB polling agency last week found that more than 90% of Greeks believed the planned cuts were unfair and a burden on the poor.
With demonstrations planned, many people fear a repeat of the violence that has hit the streets in previous protests.
Thousands of police have been deployed in the centre of Athens to prevent a flare-up.
Greece is currently trying to qualify for the next installment of its 130 billion-euro bailout, which is backed by the IMF and the other 16 euro nations.
The country was given a 110 billion-euro package in May 2010 and a further 130 billion euros in October 2011. That money is paid in installments, but correspondents say the donors are reluctant to stump up the latest slice, as they feel Greece has not made enough effort to meet its deficit-reduction targets.
Greece needs the next tranche of its bailout to make repayments on its debt burden. A default could result in the country leaving the euro.