High turnouts are normal in Greece because voting is mandatory — although that law has not been enforced in recent years.
In the country's first referendum since 1974, Greece's 9.8 million voters are choosing Sunday whether to accept demands by international creditors for more austerity measures in return for bailout loans.
Meanwhile, Germany's foreign minister says a 'no' vote in Greece's austerity referendum won't make a future compromises with the country's creditors easier — "on the contrary."
Still, Foreign Minister Frank-Walter Steinmeier says Greeks have a right to vote on the future of their country and Greece will remain a member of the 28-nation European Union even if the referendum rejects the austerity demands being made of Greece by international creditors.
Steinmeier told Berlin's Tagesspiegel am Sonntag newspaper that the debt situation in Greece, the unsolved problem of how to handle tens of thousands of migrants flooding in across the Mediterranean and Britain's demands for EU reforms are straining the EU's foundations.
He warned Sunday that a "Grexit" — Greece dropping out of the common euro currency used by 19 nations— would harm Europe's credibility in the world.