The Greek government teetered on the brink of collapse on Thursday over plans for a referendum on a euro zone bailout with turmoil in the ruling party casting grave doubt on whether Prime Minister George Papandreou can survive a confidence vote.

Conservative opposition leader Antonis Samaras demanded that a transitional government be formed immediately to run the country until snap elections, with the current parliament ratifying the financial rescue for debt-choked Greece.

Papandreou's chief of staff denied the prime minister intended to resign although sources within his PASOK socialist party said some senior lawmakers wanted a Greek former top official at the European Central Bank to head a new government.

"I don't think the government will last until tonight," said Costas Panagopoulos, managing director of pollsters ALCO.

Papandreou's surprise decision to call a referendum on the 130 billion euro bailout to save Greece from bankruptcy and prevent a global financial crisis provoked an uproar at home and across the euro zone.

Rejection of the package, which includes yet more austerity measures for the long suffering Greek electorate, would unravel the euro zone's plan for tackling its wider debt crisis, and cut off Greece's international financial lifeline.

Finance Minister Evangelos Venizelos broke ranks with Papandreou, coming out against holding the referendum after a bruising meeting with the German and French leaders, who made clear that Greece would not receive a cent more in aid until it votes to meet its commitments to the euro zone.

The cabinet was due to hold an emergency session followed by a likely meeting of PASOK lawmakers amid speculation that they will call on him to resign.

However, his chief of staff Regina Vartzeli rejected the idea. "The prime minister has not resigned and does not intend to resign," she told the website of Proto Thema newspaper.

PASOK has 152 deputies in the 300-member parliament.

If the government fell and snap elections were called, the referendum would be canceled. The bailout would have to be approved by the next parliament that emerges from elections.