France and Germany, Europe's two central powers, clashed on Wednesday over whether the European Central Bank should intervene more forcefully to halt the euro zone's accelerating debt crisis after modest bond purchases failed to calm markets.

Facing rising borrowing costs as its 'AAA' credit rating comes under threat, France appeared to plead for stronger ECB action, adding to mounting global pressure spelled out by U.S. President Barack Obama.

Bond market turmoil is spreading across Europe. Italian 10-year bond yields have risen above 7 percent, unaffordable in the long term. Yields on bonds issued by France, the Netherlands and Austria -- which along with Germany form the core of the euro zone -- have also climbed.

The ECB's role is to ensure the stability of the euro, but also the financial stability of Europe. We trust that the ECB will take the necessary measures to ensure financial stability in Europe, government spokeswoman Valerie Pecresse said after a cabinet meeting in Paris.

Pecresse said Paris believed the risk premium investors are demanding to hold French debt rather than 'safe-haven' 10-year German Bunds is not justified. That premium, or spread, hit a euro-era peak of 195 basis points on Wednesday.

But German Chancellor Angela Merkel made clear Berlin would resist pressure for the central bank to take a bigger role in resolving the debt crisis, saying European Union rules prohibited such action.

The way we see the treaties, the ECB doesn't have the possibility of solving these problems, she said after talks with visiting Irish Prime Minister Enda Kenny.

The only way to recover markets' confidence was to implement agreed economic reforms and build a closer European political union by changing the EU treaty, Merkel said.

ECB policymakers continue to reject international calls to intervene decisively as Europe's lender of last resort, stressing that it is up to governments to resolve the debt crisis through austerity measures and reforms.

SHORT RESPITE

Traders said the ECB bought Spanish and Italian bonds on Wednesday, but the respite was short and there was no sign of a change in its policy of limited, stop-go purchases to calm markets temporarily while maintaining pressure on governments.

European shares closed lower and Wall Street fell as investors doubted the ability of governments in the euro zone to contain the crisis.

Obama, on a visit to Australia, turned up the heat on Europe to act more boldly to extinguish the bush fire.

Until we put in place a concrete plan and structure that sends a clear signal to the markets that Europe is standing behind the euro and will do what it takes, we are going to continue to see the kinds of market turmoil we saw, he said.

Obama said that, while new unity governments in Italy and Greece represented progress, Europe still faced a problem of political will.

Mario Monti was sworn in as Italy's new prime minister, his main task being to push through unpopular reforms designed to placate financial markets that have driven Italy's borrowing costs to untenable levels.

His government of 16 experts features several academics and Intesa bank Chief Executive Corrado Passera.

Monti, a respected economics professor and former EU commissioner, kept the key economy portfolio for himself in a drive to implement long-delayed structural reforms and austerity measures.

All this will, I trust, translate into a calming of that part of the market difficulty that concerns our country, said Monti, who unveils his austerity program on Thursday.

Some analysts say the cabinet of technocrats could be vulnerable to ambushes in parliament, but Monti said the absence of politicians in the team would free its hands.

Federico Ghizzoni, chief of Unicredit, said he would ask the ECB to increase access to central bank funds for Italian banks, whose funding problems have grown since Italy was sucked into the debt crisis in July.

SYSTEMIC CRISIS

European Commission President Jose Manuel Barroso told the European Parliament the euro zone faced a systemic crisis and fragmenting the European Union was no solution.

In Greece, technocrat prime minister Lucas Papademos, a former ECB vice-president, won a confidence vote in parliament for his interim government despite the refusal of the main conservative leader to sign up to more austerity.

New Democracy party chief Antonis Samaras refused to bow to EU demands for a written commitment to the bailout program and called for elections in three months to restore social peace.

New data showed that Greece's austerity-fueled recession had widened the budget deficit in October, the government failing to boost revenues despite unpopular new taxes.

With Papademos's national unity coalition already split, rebuilding Greece's shattered finances to avert default will be a daunting task as Europe battles to prevent its debt woes from engulfing the entire currency bloc and hurting global growth.

And there are growing signs of strain in the money market, the plumbing of the international financial system.

Banks in the euro zone are finding it harder to obtain dollar funding. While the stresses are nowhere the levels of the 2008 financial crisis, they have continued to mount despite ECB moves to provide unlimited liquidity to banks.

With a Brussels think-tank warning that France's economy should be ringing alarm bells, Finance Minister Francois Baroin sought to calm fears about French finances.

We are expecting a slowdown, but not a recession, Baroin told the LCI news channel. We are doing everything to maintain our credit rating, to borrow more cheaply.

Data on Tuesday showed the economy of the 17-nation euro zone barely grew in the third quarter. ECB President Mario Draghi has said the bloc will be in a mild recession by the end of the year.

Many analysts believe the only way to stem the contagion for now is for the ECB to carry out the sort of quantitative easing undertaken by the U.S. and British central banks.

The ECB has bought 187 billion euros in government bonds since May 2010 but it has so far sterilized all purchases by taking the equivalent amount in from the market in deposits. One option would be to stop fully sterilising bond purchases.

This has been anathema in Germany, which fears that printing money could stoke inflation.

But Peter Bofinger, a member of the group of economists that advises the German government, said on Tuesday the ECB should act as the euro zone's lender of last resort if the bloc's debt woes risked tearing apart the financial system.

(Additional reporting by Emelia Sithole-Matarise in London, Gareth Jones and Dina Kyriakidou in Athens, Deepa Babington in Rome; writing by Paul Taylor and Jon Boyle)