European Union leaders drew a line in the sand for Greece over its debt rescue and a shock referendum, warning on Wednesday before a G20 summit that the bailout is the last offer.
The re-ignited eurozone debt crisis now poses the main risk of recession in the global economy, a central issue for the G20 summit opening on Thursday.
The referendum shock also raises the spectre of Greece leaving the eurozone if Greeks reject the rescue terms, and it has put Italy in danger over its debt mountain.
French President Nicolas Sarkozy, German Chancellor Angela Merkel, top EU leaders and the head of the IMF were to hold Greek Prime Minister George Papandreou to account for the crisis his referendum announcement has relit.
"For us, it is actions that matter. We agreed a programme with Greece last week. And from the EU side, at least for Germany, we want to implement this programme," Merkel told reporters before flying to the French Rivieria.
"For this, we need clarity and that's what these talks tonight are about," she added.
And the message from Sarkozy in an unusual statement late on Tuesday and from the German Foreign Minister Guido Westerwelle in Ankara on Wednesday was clear: the complex Greek-eurozone rescue strategy agreed in extremis last week is a take-it or leave-it offer.
Westerwelle said: "The whole programme we just agreed last week cannot be placed back on the table."
Sarkozy insisted that the deal "is the sole possible way to resolve Greece's debt problems."
Europe has come under intense pressure from its G20 partners to contain its debt crisis, and after hard-fought negotiations last week came up with a deal that would wipe 100 billion euros off Greece's debt, strengthen banks to weather those losses and more than double the firepower of its bailout fund.
With Greek voters bitter after enduring over a year of painful austerity measures, markets were spooked by the possibility that it could be rejected, which would likely mean the country would go bankrupt and be forced to leave the eurozone.
European stock markets fell heavily on Tuesday, and Italian borrowing rates rose sharply. European markets steadied on Wednesday, after Asia stocks finished mixed but tension on the eurozone bond market increased.
The euro rose to $1.3804 from $1.3697 in New York late on Tuesday.
A French government source said Sarkozy and Merkel were set to tell Papandreou on Wednesday that the referendum should be on whether or not Greece stays in the eurozone.
That would be the first time that France and Germany have so explicitly raised the possibility of a country abandoning the euro.
A recent Greek poll indicated that most Greeks favour staying in the eurozone, despite hostility towards the tough rescue conditions.
"The Greeks must say quickly and without ambiguity if they want to keep their place in the eurozone or not," French Prime Minister Francois Fillon said in Paris.
Papandreou has said: "The referendum will be a clear mandate, but also a clear message inside and outside Greece on our European course and our euro membership."
Athens is also expected to come under pressure to have the Greek parliament quickly back the bailout deal, with the release of 8.0 billion euros in rescue loans needed in the next few weeks for the country to avoid a default, and also to hold the referendum soon to reduce dangerous uncertainty.
European Commission chief Jose Manuel Barroso warned that "without the agreement of Greece to the EU-IMF programme, the conditions for Greek citizens would become much more painful, in particular for the most vulnerable.
"The consequences would be impossible to foresee."
But German Finance Minister Wolfgang Schaeuble said: "If Greece will accept the burden and efforts required by the aid programmes, if it wants to stay within the eurozone, then we will support it."
The Greek referendum announcement blew out of the water European hopes to show up at the G20 summit with a plan to deal with its debt crisis, as well as hopes to secure financial support.
The eurozone's troubles are increasing threatening to spill outside of Europe and the OECD warned earlier this week a quick resolution was key to ensure a rebound in the world economy.
EU Energy Commissioner Guenther Oettinger warned the delay entailed by holding a referendum, which Athens has suggested holding in January, has "endangered" the single currency.
Asian G20 members China, Japan and India heaped further pressure Wednesday on Europe to get its house in order.
"China sincerely wants stability for the eurozone and the euro," President Hu Jintao told the French newspaper Le Figaro, but without saying what China could do to help Europe resolve its crisis, notably by participating in a rescue fund for indebted EU countries.
