International Monetary Fund managing director Christine Lagarde has called for the world's leading countries to act now and work together to ensure economic recovery.
''We are linked by a common destiny,'' she said at the annual meetings of the IMF and the World Bank in Washington - after another week of volatility on world share markets.
''And these turbulent times must bind us ever closer together.
''There is a path to recovery. It's narrower than it was three years ago but there is a path and we have options."
But Ms Lagarde added:
''There are dark clouds over Europe and there is huge uncertainty in the US. And with that we could risk a collapse in global demand.
''Well, so what? Let's remove the clouds and remove the uncertainty. Easier said than done, and it requires clearly a collective action.
''We are all in it together and nobody should be under any illusion that there could be a de-coupling.''
Meanwhile British Chancellor George Osborne has warned time is running out to tackle the eurozone debt crisis.
Speaking in Washington, where the G20 is also gathering, Mr Osborne said European leaders had six weeks to end the crisis.