Greece's finance minister said Sunday aid will arrive in time to avert the euro zone's first sovereign debt default as signs grew that a 45 billion-euro ($60.49 billion) rescue would have to be bigger.

Finance Minister George Papaconstantinou said bailout talks with the International Monetary Fund and European partners went well and he was confident Greece would secure help in May to finance its crippling public debt.

Papaconstantinou also sent a warning to investors who have been betting that Greece will default: All I can say is that they will lose their shirts.

Saddled with huge debt and a swollen deficit, Greece bowed to intense pressure from financial markets Friday and formally requested aid, triggering what would be the first bailout of a member of the 11-year-old single currency bloc.

Athens has already announced billions of euros in budget cuts, including tax hikes and reductions in public sector wages, setting off violent protests and strikes.

Now it is in talks with the European Union and IMF on additional steps to get the aid flowing.

Papaconstantinou played down concerns that Germany, facing a key regional election in early May, might block a rescue deal that is hugely unpopular in Europe's biggest economy.

Even if there are delays in getting parliamentary approval in some European countries, IMF support could be matched with bridge loans from European countries that had already cleared the deal, the minister told a news conference at the IMF.

IMF Managing Director Dominique Strauss-Kahn said the Greek aid talks had accelerated and he expressed confidence in Greece's determination to get its economy back on track.

MORE THAN PLANNED

Canada's Finance Minister Jim Flaherty said the package would end up being more than had been said previously, declining to specify the amounts being discussed.

Asked by a reporter whether aid could be as much as 80 or 90 billion euros, Papaconstantinou said he could not provide specific figures.

French Economy Minister Christine Lagarde pointed out that the 30 billion-euro commitment from euro zone countries was just for the first year of a three-year package and talks were going on about what would come after that.

IMF and European funding would be disbursed simultaneously, Papaconstantinou said, addressing speculation that the IMF might lend Greece money quickly if Europe drags its feet.

The IMF is expected to provide one-third of the aid.

Financial analysts said investors were waiting for details on how much money Greece would get and what further austerity measures it will take in return for financing.

I think a large, comprehensive and most importantly expeditious package will help steady market expectations, said George Hoguet, global investment strategist at State Street Global Advisors.

GREECE PLEDGES TOUGH MEASURES

Mindful of opposition to bailing out Greece, German Finance Minister Wolfgang Schaeuble warned Athens that an overhaul of its economy was unavoidable and an absolute prerequisite if Berlin and the EU were to approve the aid.

Papaconstantinou responded saying Greece was already taking tough measures and the rescue would include strict conditions.

He said Berlin was completely on board with the conditions set for Greece and noted that Germany had backed the euro zone's decision to make support available to Greece.

France's Lagarde promised to hold Greece accountable for unsuitable economic policies that pushed its 2009 budget deficit to 13.6 percent of gross domestic product and its debt to 115 percent of output.

She described the aid package as a cocktail of indulgence and great strictness, telling the Journal du Dimanche weekly that Greece's partners would closely monitor progress and put their foot on the brake if Athens reneged on commitments.

Germany and France, the biggest economies in the 16-nation euro zone, are due to provide about half of the EU aid.

DOUBTS ON AID PACKAGE

Fears over the chances of a debt default have pushed the yield on Greek 10-year bonds above 8.7 percent, a whopping 567 basis points over the rates on benchmark German Bunds.

This has made it prohibitively expensive for Athens to service its mountain of debt and Greece's formal request for aid Friday did little to ease market pressures.

One big risk to Greece's economic plans is public opposition to further austerity steps. Greek riot police fired teargas at protesters who held an impromptu march through central Athens Friday to protest against more budget cuts.

A poll released Saturday showed that roughly two-thirds of Greeks believe Prime Minister George Papandreou's socialist government was either too slow to react or handled the economy poorly as the country's fiscal crisis deepened.

Center-left newspaper Eleftherotypia said the specter of Hungary was haunting Papandreou's government. Voters in Hungary booted out the socialist government this month after it tried to push through painful IMF-ordered budget cuts.

(Additional reporting by Noah Barkin in Berlin, Sophie Hardach in Paris, George Georgiopolous in Athens, Tracy Rucinski in Madrid, and Daniel Bases in Washington; Writing by Emily Kaiser and Noah Barkin; Editing by Ralph Boulton and Patrick Graham)

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