ministers, who are due to discuss Greece's bailout money on Monday.

Greece's largest labour union, the private sector GSEE, said the changes, were the "last nail on the coffin" for workers and pensioners. A spokesman said: "They are trying to prove to the Eurogroup that they are good students but they are destroying Greece's social security system."

In Athens, no public transport service was working on Friday morning as metro, tram, bus and rail workers refused to work.

Train services across the country were halted, and ferries linking mainland Greece to the islands remained anchored in port. The strike by the powerful PNO seafarers union's strike is set to last until Tuesday morning.

Air travel was not affected by the strike. Airport workers staged their own industrial action last month.

The nationwide strikesare the fourth to be called since Prime Minister Alexis Tsipras's government won re-election after organising a referendum on the country's bailout.

Mr Tsipras was elected on an initial anti-austerity pledge but later signed up to Greece's third international bailout since 2010. He has a thin majority with 153 MPs in a 300-seat parliament.