Athens is tightening its security ahead of a visit by German Chancellor Angela Merkel, her first since the eurozone crisis erupted nearly three years ago.
Some 7,000 police officers are on duty, public gatherings are banned in certain areas of the city and protesters have been warned to “protect the peace”.
The visit comes as Greece bids to pass new cuts of 13 billion euros ($17 billion) to qualify for more bailout cash.
Analysts say Angela Merkel is regarded by many Greeks as the author of austerity.
While Germany has contributed the most money in the bailing out of Greece, its chancellor is held responsible for demanding that Greece make swingeing cuts in exchange for the financing it has received.
Speaking on Monday, Jean-Claude Juncker, chairman of the Eurogroup finance ministers of the eurozone, raised the pressure on Greece, calling on the government to demonstrate it could implement planned reforms “by 18 October at the latest” to qualify for the next bailout installment of 31.5 billion euros.
He was speaking as the eurozone’s new permanent fund to bail out struggling economies and banks was formally launched at the finance ministers’ meeting.
There has been growing unrest in Greece at the planned new cutbacks.
Police have banned protests on Tuesday in much of central Athens, and within a 100-metre (110-yard) radius of the route Angela Merkel’s motorcade will travel – although two planned protests elsewhere in the city will go ahead.
On Monday, public order minister Nikos Dendias appealed to protesters to “protect the peace, and above all our country’s prospects and our international image”, Reuters news agency reported.
Angela Merkel, a target for popular dissent, will be in Athens for about six hours, and will have talks with Greek Prime Minister Antonis Samaras.
The meeting is a gamble.
If there is chaos on the streets, it will only underline for the German public that Greece is a lost cause.
But Angela Merkel’s visit – her first to Greece in five years – is sending a symbolic message that she wants Greece to stay in the eurozone.
Meanwhile, the International Monetary Fund said on Monday that the global economic recovery was weakening, with government policies having failed to restore confidence.
It added that the risk of further deterioration in the economic outlook was “considerable” and had increased.