Greece's prime minister faces a grilling from the leaders of Germany and France on Wednesday after fighting to win the backing of his cabinet to hold a referendum on a 130 billion-euro ($178 billion) bailout package.

French President Nicolas Sarkozy and Germany's Angela Merkel summoned George Papandreou for crisis talks in Cannes, before a G20 summit of major world economies, to push for rapid implementation of measures to tackle the euro zone debt crisis, which Athens has thrown into doubt.

"This announcement took the whole of Europe by surprise," Sarkozy said on the steps of the Elysee Palace in Paris. "The plan... is the only way to solve Greece's debt problem."

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 last week to corral its sovereign debt crisis.

Some of Papandreou's party called for him to quit, accusing him of endangering Greek euro membership with his shock decision to call a popular vote, a move that pummelled the euro and global stocks.

But the cabinet support at least gives him a stay of execution before a confidence vote in parliament on 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 cabinet meeting that lasted seven hours.

Even if he wins the confidence vote, the euro zone faces weeks of uncertainty in which markets can create havoc. Lose and Greece faces disorder which would hammer Europe's banks and threaten the much larger economies of Italy and Spain, which the currency bloc may not have the resources 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.

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 have suggested it would probably be held in mid-January but the interior minister said it could happen as early as December.

Opinion polls suggest most Greeks think it is a bad deal, 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.