Greek journalists have walked off the job ahead of a general strike set to disrupt services across the country to protest pension reforms that are part of the country's third international bailout.

Wednesday's media strike pulled all news broadcasts off the airwaves and left news websites without updates, while no Thursday newspapers will be printed.

Unions have called for a nationwide general strike on Thursday that will shut down everything from state schools to public offices, while state-run hospitals will operate on emergency staff only. Public transport, including domestic flights, will also be disrupted.

Overhauling the pension system is one of the main reforms the government must make, but critics say it will lead to dozens of professions paying most of their income in social security contributions and taxes.