Germany and the rest of the euro region are bracing for more Greek political upheaval followed by tortuous negotiations, even if the country votes for more austerity in Sunday's referendum.

There is no quick fix to the crisis because European Union rules make talks on financial aid difficult to restart, according to an official in Chancellor Angela Merkel's government.

Adding to the murky landscape are polls showing the outcome of the referendum on austerity was too close to call.