China's growth seemed to have passed its trough, the OECD said, and it was expected to pick up to an annualised pace of around 8 per cent by the end of the year.
"In many emerging economies, however, loss of domestic activity momentum, together with the shift in expectations about the course of monetary policy in the United States and the ensuing rise in global bond yields, have led to significant market instability, rising financing costs, capital outflows and currency depreciations," it said.
"Countries that have relied heavily on portfolio inflows to finance large current account deficits have been most affected."
India, Brazil, South Africa and Indonesia have all seen double-digit percentage falls in their exchange rates since May at the same time as global long-term interest rates have risen, triggered by the prospective withdrawal of additional quantitative easing measures in the United States in the light of growing evidence the US economy is strengthening.
"As emerging economies contributed the bulk of global economic growth in recent years, and since their share of global output has increased so much, this widespread loss of momentum makes for sluggish near-term growth prospects for the world economy."
One of the risks to the global outlook the OECD saw was that strong capital outflows from, and financial market volatility within, some emerging markets could intensify.
Another risk is posed by unresolved debt issues in the eurozone.
"Many euro area banks are insufficiently capitalised and weighed down by bad loans."
The third risk the OECD cited was renewed deadlock and brinkmanhip over fiscal policy in the United States, which it said had the potential for seriously negative consequences. "Failure to reach agreement on a timely basis on raising the federal Government's debt ceiling, which would be reached in October, or on an appropriation for 2014 or a continuing resolution, could lead to disruptions in government spending and trigger adverse reactions in financial markets or weaken confidence."
