A G20 summit of the world's biggest economies is under way in Cannes, in southern France, with the issue of the Greek debt crisis commanding the most attention.
US President Barack Obama has pledged to stand with European leaders to resolve the eurozone crisis, but he wants its financial problems dealt with quickly.
Speaking alongside French President Nicolas Sarkozy after the two met privately on the sidelines of the Group of 20 summit on Thursday, Obama said that resolving the European financial crisis is "the most important aspect of our task over the next two days".
"We're going to have to flesh out more of the details about how the plan will be fully and decisively implemented," he said.
At a later meeting with German Chancellor Angela Merkel, Obama said: "We are now, having seen some progress, looking forward to working together to figure out how we can implement this in an effective way, to make sure that not only is the eurozone stable but the world financial system is stable as well.''
Al Jazeera's Jacky Rowland, reporting from Cannes, said: "The European leaders meeting here in Cannes have really been riding a kind of Greek roller-coaster over the last 48 hours or so.
"[Obama] made it clear that this is not a crisis that just affects European leaders but has an impact on the whole world. We only have to look at the kind of volatility recently that there has been on the euro-dollar exchange rate to see why people like President Obama are telling the European leaders that they need clarity and detail about how this rescue plan is going to be implemented."
Obama, however, is not the only world leader concerned about the Greek crisis, our correspondent said.
Russian President Dmitry Medvedev, speaking on the sidelines of the Cannes summit, urged Europe to move swiftly to contain the debt crisis.
"I am convinced that due to the size of the European economy no outside aid can become a decisive factor for the
eurozone and the first and the most simple conclusion is - Europe should help itself, the European Union has everything for that today - the political authority, the financial resources and the backing of many countries," Medvedev said.
Medvedev said Russia is willing to help the eurozone to overcome the crisis.
"Russia is a part of Europe and we are no indifferent to the problems of the European Union," he said, "and secondly we are ready to participate in the programmes of financial assistance to the EU countries first of all through the instruments of the International Monetary Fund.
"The actions of our [European] partners should be much more active, much more decisive to bring order, otherwise
we will be hostages of these problems for a long period of time and all delays such as referendums or something else
will not help to resolve the issue."
While fast-moving events in Athens overshadowed the first day of the G20 summit, Al Jazeera's Rowland said other important issues inevitably took a back seat.
"Certainly, the effect of all this inevitably has been to overshadow some of the other really important issues that were due to be discussed at this summit, that will still be discussed at this summit," she said.
"Things like efforts to try to make global growth more sustainable, and the idea that it shouldn't just be this divide between wealthy developed countries and poorer countries who are traditionally the recipients of aid."