Germany, France and debt-mired Greece agreed Tuesday to hold a fresh round of talks on the euro crisis after US President Barack Obama urged Europeans to greater efforts to calm volatile markets.Markets cheered news that German Chancellor Angela Merkel, French President Nicolas Sarkozy and Greek Prime Minister George Papandreou would hold a teleconference Wednesday regarding Athens\'s debt emergency.\"The teleconference was decided in view of the upcoming EU meeting in Poland,\" a Greek official told AFP, referring to informal talks between EU finance ministers and central bankers in Wroclaw on Friday and Saturday. Merkel had earlier sought to soothe traders\' fears over Greece, stressing that everything would be done to avoid an \"uncontrolled insolvency\" and emphasising the eurozone would remain intact.But her efforts to reduce market volatility were undermined by rumours -- later denied -- that Berlin and Paris were about to issue new proposals on Greece. The speculation sent European stock markets and the euro sharply higher in a roller-coaster session again dominated by the eurozone debt woes. Merkel\'s comments followed a stern warning from Obama that the global economy was unlikely to recover until the eurozone debt crisis was contained. In a roundtable interview with journalists, Obama said: \"We will continue to see weaknesses in the world economy, I think, so long as this issue is not resolved.\" The US president added that it would be a \"significant topic\" for the next G20 meeting in France and that while Washington was \"deeply engaged\" with EU countries on tackling the crisis, ultimately it was up to Europe to solve it.\"Greece is obviously the biggest immediate problem. And they\'re taking some steps to slow the crisis but not solve the crisis,\" Obama said.\"The bigger problem is what happens in Spain and Italy if the markets keep making a run at those very big countries,\" he said.The Polish EU presidency confirmed that US Treasury Secretary Timothy Geithner will attend Friday\'s meeting of EU finance ministers and central bankers. \"Participants of the meeting will focus on common EU and global efforts to counteract the current disruption in financial markets in order to return to the path of stable economic growth,\" the Polish EU presidency said. And the eurozone received an offer of help from an unlikely source as Brazilian Finance Minister Guido Mantega said the emerging economies which make up the BRICS group would discuss possible aid to Europe to ease the crisis.Earlier in the trading day, the euro dropped against the dollar and European stock markets fell as concerns over Greece weighed on the market again and it became clear that Italy wasn\'t in talks with China about buying bonds. As if to confirm Obama\'s concerns about Italy, Rome was only able to place 3.865 billion euros ($5.256 billion) in five-year bonds at new high of 5.6 percent.While Italy confirmed reports that Finance Minister Giulio Tremonti had met the head of China\'s biggest sovereign wealth fund CIC last week, officials said no request was made of Beijing to step in and purchase its bonds. \"This is a market that is all over the map -- literally -- with headlines out of China, the US, and Europe in particular driving things,\" said Patrick O\'Hare, an analyst with Briefing.com. Many analysts are concerned that Italy could be the next eurozone domino to fall, with enormous debt which stands at 120 percent of gross domestic product. Battling to prevent a debt crisis that has already claimed Greece, Portugal and Ireland as victims, Silvio Berlusconi\'s government hopes the Chamber of Deputies will Wednesday pass an austerity package to balance the books by 2013. But in an interview with Germany\'s RBB radio station, Merkel said the top priority for policymakers now was to avoid a chaotic default for Greece as this would have serious consequences for the rest of the 17-nation zone.She also stressed that the eurozone had to remain intact, warning that if Greece were to leave the group, others would swiftly follow. \"I have made my position very clear that everything must be done to keep the eurozone together politically. Because we would soon have a domino effect,\" said the chancellor. Meanwhile in Greece, authorities were bracing for a new round of strikes to protest against new civil service pay and job cuts, as well as an unexpected fresh property tax translating into hundreds of euros per person on average.EU officials have warned repeatedly that Athens will not receive the next slice of aid, worth eight billion euros, unless it can persuade an international team of observers that it can swiftly reduce its deficit pile. Reform laws voted months ago have yet to be put into practice, and a crash privatisation programme has made little tangible progress, raising fears Athens will soon simply run out of money.On Monday, deputy finance minister Filippos Sachinides said the government had enough cash to last until October.Merkel combined a carrot-and-stick approach, saying she was making it clear to Athens \"in direct contacts\" with Greek authorities \"how serious the situation was\" but adding also that Athens was making some progress. \"Everything I hear from Greece is that the Greek government has hopefully seen the writing on the wall and is now doing some of the things that are required,\" she said.