Spreading fears about a Greek debt default and contagion to larger economies in the euro zone have raised alarm in the United States and among emerging market heavyweights about the risk of a potentially major shock to an ailing global economy.

At talks among the Group of 20 major economies and at the International Monetary Fund (IMF) in Washington, the United States and big emerging economies such as China, Brazil and India are likely to join the IMF and call on Europe to be more decisive.

The event is the third gathering of finance chiefs in three weeks, after G7 and EU ministers made little headway in tackling the crisis during each of the last two weekends.

European ministers continue to say that belt-tightening remains their priority. German officials said they will stress the need to cut deficits at this week's talks.

The Washington talks come about three weeks ahead of another G20 ministerial meeting in Paris. It will aim to finalize details on a deal to reduce global trade and financial imbalances ahead of a G20 leaders’ summit in November.