The US, China and other countries have piled increasing pressure on Europe to come to grips with its debt crisis before it risks causing bank runs and pushing the global economy into ruinous recession.
The semi-annual gathering of the IMF and World Bank was dominated on Saturday by worry about the risk that Europe now poses to the rest of the world.
The IMF said it will take decisive action to tackle the eurozone debt crisis and support the global economy by reviewing the resources it has available to tackle the crisis.
Timothy Geithner, US treasury chief, said it was time for the European Central Bank to take a more central role in fighting the crisis, in his most explicit warnings to date.
"The threat of cascading default, bank runs and catastrophic risk must be taken off the table, as otherwise it will undermine all other efforts, both within Europe and globally," Geithner told the International Monetary Fund.
Financial markets have been wracked by fears the Greek debt crisis could overwhelm other euro zone countries and banks.
Meanwhile, IMF chief Christine Lagarde said on Saturday the IMF's financial resources would not be enough to meet potential crisis needs.
"Our lending capacity of almost $400bn looks comfortable today but pales in comparison with the potential financing needs of vulnerable countries and crisis bystanders," Lagarde said.
Investors took some comfort on Friday from signs of new resolve by European officials to bolster their defences after nearly two years of what many see as half-hearted action.
"The one word Lagarde kept using was 'implementation' ... meaning enlargement of the European rescue fund to the tune of $600bn," Al Jazeera's Tom Ackerman said, referring to "what was already committed to be done back in July".
But many policymakers now talk openly of possible Greek default and the need for Europe to move much more aggressively to cope with it.
"Decisions as to how to conclusively address the region's problems cannot wait until the crisis gets more severe," Geithner said.
Zhou Xiaochuan, China's central bank governor, also urged quick action to bring greater financial stability to the European region.
"The sovereign debt crisis in the euro area needs to be resolved promptly to stabilize market confidence," Zhou told the IMF. "Forceful and credible fiscal consolidation measures are needed in relevant economies to alleviate sovereign debt stress."
A default by Greece could cause a domino effect in other highly indebted euro zone countries, officials fear, putting at risk Europe's banking system given the size of holdings of debt issued by weak European nations.
Canada's central bank governor, Mark Carney, told Canadian radio that the euro area's bailout fund should be more than doubled to "the neighborhood of a trillion euros".
Geithner wants more co-operation among European policymakers - who set their own tax and fiscal policy - and their central bank, which is mandated to focus on keeping inflation low.
"European governments should work alongside the ECB to demonstrate an unequivocal commitment to ensure sovereigns with sound fiscal policies have affordable financing," Geithner said.
The US has been pushing for a heightened role for the ECB, pointing to the way that the treasury and the Federal Reserve co-operated during the 2007-2009 financial crisis, which threatened to engulf the US banking system.
One option would be for the ECB to commit large amounts of funding, with the European Financial Stability Facility, Europe's temporary bailout fund, putting forward money to cover potential losses.
A senior lawmaker from German Chancellor Angela Merkel's conservatives said the euro zone's permanent rescue mechanism should be introduced sooner than mid-2013 to beef up private creditors' response to the Greek debt crisis.
Geithner and Fed Chairman Ben Bernanke met on Friday with top officials from the ECB and other national central banks from Europe, in part to discuss international financial regulatory reform.
In a reminder of how sensitive some European officials are to the ECB taking a more active role in the crisis, a board member of Germany's central bank, the Bundesbank, suggested the time was coming for the ECB to stop buying government bonds.
"I think the time is coming for this to stop," Joachim Nagel, said, insisting that the ECB's bond buying was only supposed to be a temporary measure until the euro zone's bailout fund is beefed up.
Another top ECB official sought to quash growing expectations that Greece will eventually default.
ECB Governing Council member Athanasios Orphanides said the idea of a Greek default was "surreal" but warned that it could occur as the result of a "political accident".
Greece is in tense talks with the IMF and European authorities to secure a new 8 billion-euro installment of its rescue package.
In return, Athens has pledged deep austerity measures but negotiators are frustrated at what they say is Greece's slow reform pace. October's loan payment, however, is still widely expected to be made. The next installment is due in December.
Germany, as the strongest economy in Europe, plays a central role in any effort to curb a debt crisis, but public opinion there has turned against further big bailouts for fellow euro zone countries.