Greek labour unions are staging a nationwide strike to protest against austerity policies imposed on the country by its foreign creditors, including Germany, whose chancellor, Angela Merkel, will visit Athens this week.

Schools and pharmacies were shut, ships remained docked at ports, hospitals operated on emergency staff and transport in Athens was disrupted on Wednesday due to the walkout called by private sector union, the General Confederation of Greek Workers (GSEE), and its public sector counterpart, the Civil Servants' Confederation (ADEDY).

Thousands of striking workers, pensioners and the unemployed were expected to march to parliament around noon.

"This is our answer to the dead-end policies that have squeezed workers and made Greek people miserable," GSEE said in a statement. "We are striking and fighting to put an end to austerity".

Unions said their anti-austerity message was also aimed at Merkel, who is due to meet Greek Prime Minister Antonis Samaras in Athens on Friday. Germany has insisted on painful spending cuts and tax hikes in return for international loans.

GSEE and ADEDY have staged dozens of strikes since Greece's first bailout in 2010, saying the measures prescribed by the European Union and the International Monetary Fund have hit the poor and worsened its six-year recession.

But protests have largely fizzled out, with low turnout blamed on a growing mood of resignation and protest fatigue.

Income razed

Political analysts will be watching the turnout in Wednesday's street protests.

The disruption is expected to be most keenly felt in maritime transport such as the ferry services to and between the Greek islands and also on the railways.

Greeks have lost about a third of their disposable income since the debt crisis started and unemployment has soared, leaving more than a quarter of people without a job.

Samaras' coalition government has been basking in the glow of its latest deal with inspectors from the troika of the European Union, European Central Bank and International Monetary Fund, clinched after nearly seven months of wrangling over issues such as deregulating the milk sector and pharmacies.

Athens is set to return to international bond markets for the first time since 2010 later this month, possibly as soon as this week, by selling a five-year bond to investors.

The government qualified for further rescue loans after it passed a reform law required by the lenders last month, but it saw its parliamentary majority reduced to just two seats after it had to expel one politician who failed to support it.

Days later, a scandal over the prosecution of far-right politicians helped the leftist opposition halt a rise in support for the government, a poll showed.