Athenians have gone without public transport and services faced disruption nationwide as Greek unions went on strike in protest over further creditor-demanded measures due to be voted on in parliament.
The new reforms include tougher conditions for unions to call strikes, speedier property foreclosures and limitations on family benefits.
The measures are key for Greece to receive further bailout funds.
The package is expected to be approved later today by MPs from the governing left-led coalition, although opposition parties have rejected it.
Unions shut down all public transport in the Greek capital, while state-run schools and public hospitals also faced disruptions as teachers and doctors participated in stoppages.
Dozens of flights are being either rescheduled or cancelled due to a three-hour walkout by air traffic controllers.
Unions are planning three separate protest marches in central Athens, starting just after midday and culminating in the evening.
The more than 1,500-page austerity bill is considered to be potentially the last major package of spending cuts and reforms before Greece formally ends its bailout programme in August.
The country has depended on emergency loans from three successive bailouts, funded mainly by other eurozone members, since 2010 after it lost the ability to raise money on international bond markets.