Turmoil in emerging markets this summer has forced the International Monetary Fund into a humbling series of U-turns over its global assessments.

In a confidential note the IMF has dropped its view of emerging economies as the dynamic engine of the world economy, instead noting that “momentum is projected to come mainly from advanced economies, where output is expected to accelerate”.

The note, produced for world leaders attending the G20 summit in St Petersburg this week, urges them to act to mitigate risks from weakness in poorer countries. However, its clout is likely to be diminished by the IMF's failure to provide an accurate assessment of the world economy as recently as its meetings in April.

The IMF did warn then that the end of extraordinarily loose monetary policy in advanced economies might cause turmoil in financial markets and sharp depreciations in emerging economy exchange rates.

But the IMF concentrated on describing a “three-speed recovery” with strength in emerging economies, the US on the mend and European economies still in stagnation and reflected this view in those forecasts.

In the note for the G20 it admits “recent indicators point to stronger underlying activity in several advanced economies while key emerging economies have slowed”. – Copyright The Financial Times Limited 2013