By Emmanuel Jarry and Dina Kyriakidou
French President Nicolas Sarkozy and Germany's Angela Merkel summoned George Papandreou for emergency talks in Cannes on the eve of a G20 summit of major world economies, to push for rapid implementation of measures to tackle the currency area's debt crisis, which Athens has thrown into doubt.
EU and IMF board sources said Greece would not receive an urgently needed 8 billion euro aid installment, due this month, until after the vote because official creditors wanted to be sure Athens would stick to its austerity program.
Sarkozy has said Papandreou's announcement of a referendum "took the whole of Europe by surprise" and his prime minister, Francois Fillon, told parliament: "Europe cannot be kept waiting for weeks for the outcome of the referendum.
"The Greeks must say quickly and without ambiguity whether they choose to keep their place in the euro zone or not."
Opinion polls suggest most Greeks think the deal thrashed out by euro zone leaders last week is a bad one, but much will depend on how Papandreou frames the debate, either on the bailout -- and the painful cuts it demands -- or membership of the euro, which remains popular.
Greece's European partners will press for the latter.
German Chancellor Merkel struck the same tone of exasperation and impatience as Fillon in comments before flying to Cannes for hastily arranged meetings of European Union policymakers (1630 GMT) and with Papandreou (1930 GMT).
"We agreed a plan for Greece last week. We want to put this plan into practice, but for this we need clarity and the meeting tonight should help with precisely this," she said.
French officials said Papandreou would be pressed to put the bailout deal to parliament before the referendum, in hopes of reassuring financial markets, and to hold the plebiscite by mid-December to avoid months of uncertainty.
A German Finance Ministry spokesman said Greece apparently had enough money to keep running until mid-December, when it has to redeem more than 6 billion euros in debt.
WEEKS OF UNCERTAINTY
Win or lose, Papandreou's gamble guarantees weeks of uncertainty just as the 17-nation European currency area is desperate for a period of calm to implement the remedies agreed to corral its sovereign debt crisis.
Some in Papandreou's party called for him to quit, accusing him of endangering euro membership with his shock decision to call a popular vote, a move that pummeled the euro and stocks.
The Socialist prime minister battled late into the night to win cabinet support, giving him at least a stay of execution before a confidence vote in parliament Friday.
"The referendum will be a clear mandate and a clear message inside and outside Greece on our European course and participation in the euro," Papandreou told a seven-hour cabinet meeting that ended early Wednesday.
"Without the agreement of Greece to the EU/IMF program, the conditions for Greek citizens would become much more painful, in particular for the most vulnerable. The consequences would be impossible to foresee," he said.
If Papandreou wins the confidence vote, the euro zone faces a period of policy vacuum in which markets can create havoc. If he loses, Greece faces a disorderly default which would hammer Europe's banks and threaten the much larger economies of Italy and Spain, which the bloc may not have the means to bail out.
As a result, the Greek premier's move has aroused anger and surprise in equal measure around the world.
"That's enough now: Greeks out!" Kronen Zeitung, Austria's biggest-selling paper, said on its front page.
The chairman of euro zone finance ministers, Jean-Claude Juncker, said Greece could go bankrupt if voters rejected the bailout package and Japanese Finance Minister Jun Azumi said: "Everyone is bewildered."
ECB IN SPOTLIGHT
Doubt about Europe's ability to contain the debt crisis has once more sent markets into a spin and put Italy firmly in the firing line.
The risk premium on Italian bonds over safe-haven German Bunds hit a euro-lifetime high Tuesday, despite European Central Bank buying of its bonds.
Ireland's finance minister said the ECB would be forced to pledge "a wall of money" to buy bonds, something many of its policymakers are deeply uncomfortable about.
Until the Greek situation is clearer, last week's package of measures is likely to be in limbo, leaving the ECB as the only bulwark against market attacks.
But the man representing banks in the negotiations on a "voluntary" writedown, Charles Dallara of the Institute of International Finance, said it was continuing to work on technical details of the plan.
Greek Conservative opposition leader Antonis Samaras said Papandreou had acted as a one-man roadblock.
"How can banks accept a haircut on their debt if they don't know if Greece accepts it in the first place?" he told lawmakers in a speech. "Papandreou has put the country in the center of a global storm ... a government in such a state of panic is dangerous and must leave as soon as possible."
TIMING, RESULT IN DOUBT
Greek government spokesman Ilias Mosialos said the referendum would take place "as soon as possible, right after the basics of the bailout deal are formulated."
Greek officials had suggested it would probably be held in mid-January but the interior minister said it could happen as early as December.
The Greek press, including dailies traditionally friendly to the government, almost unanimously condemned Papandreou.
Center-left newspaper Eleftherotypia described the prime minister on its front page as "The Lord of Chaos." Ethnos, another pro-government paper, called the referendum "suicidal."