President Nicolas Sarkozy of France and Chancellor Angela Merkel of Germany have warned that Greece must decide if it wants to abide by the terms of a bailout deal and to stay in the euro.
Sarkozy warned that not a further cent in rescue loans would be transferred until Greeks made a clear response, with Athens set to run out of funds and default in weeks unless it receives eight billion euros.
"We hope to pursue Europe with our Greek friends," Sarkozy told a press conference following crisis talks with Greek Prime Minister George Papandreou, German Chancellor Angela Merkel and EU and IMF officials in Cannes, France, on Wednesday.
On Monday, Papandreou shocked Europe by saying he would put the terms of a bailout deal agreed last week with European leaders to a referendum, sending panic through markets which thought the rescue plan a done deal.
Without the eight-billion euro transfer, Greece could face a ruinous debt default within weeks, experts predict.
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The Greek leader said after meeting the European leaders "that we could move the referendum as soon as possible, organise it as soon as possible, and we believe that we can have a referendum on the 4th of December."
He insisted that it was the "democratic right" of the Greeks to vote on the bailout plan - which foresees more tight austerity measures - but added: "I believe that the Greek people want to be in the eurozone."
He conceded however that the popular vote put the country's euro membership at stake: "This is a question of whether we want to remain in the eurozone. That's very clear."
Mr Sarkozy said Greece needed to play by the rules.
"The Greeks have to decide whether to continue the adventure with us or not," Sarkozy warned.
"We hope to continue with the Greeks, but there are rules that have to be respected."
"The Europeans and the IMF can't release the sixth tranche of loans to Greece until Greece endorses the package of October 27," Sarkozy said, calling for the referendum "if one is needed" to be carried out swiftly.
Ms Merkel said the rest of the EU would listen to the Greek people, as well.
"If the Greeks say they do not want to stay in the euro, we will accept it, but we will not abandon the euro", she said.
If the provisions of the loan agreements are not respected "neither Europe nor the IMF can release even a further cent".
Speaking after Wednesday's talks, Papandreou said: "The essence in this is not the question only of a program, this is a question of whether we want to remain in the eurozone. That's very clear.
