WASHINGTON, Aug 19 (AFP) – The global recovery from recession depends on a delicate rebalancing of economies – notably between the United States and Asia – to sustain it, the chief IMF economist said.

''The recovery has started. Sustaining it will require delicate rebalancing acts, both within and across countries,'' Olivier Blanchard said in an IMF article, released in advance of publication Wednesday.

Blanchard cautioned that predictable models based on past recoveries from recessions would not apply to the worst global slump since World War II.

''The world is not in a run-of-the mill recession. The turnaround will not be simple. The crisis has left deep scars, which will affect both supply and demand for many years to come,'' he said.

In its latest economic forecasts, the IMF estimated in July a global contraction of 1.4 percent in 2009, followed by sluggish growth of 2.5 percent in 2010.

The United States, the epicenter of the crisis, ''is central to any world recovery,'' Blanchard said in the article titled ''Sustaining a Global Recovery.''

Blanchard said two rebalancing acts will have to come into play to sustain the global recovery: a switch from public to private spending and the rebalancing of international trade flows.

The latter would require ''a shift from domestic to foreign demand in the United States and a reverse shift from foreign to domestic demand in the rest of the world, particularly in Asia,'' he said.

Pointing to a decline in American household consumption – which ''represents 70 percent of total US demand'' – and a rise in the personal saving rate that is expected to persist for some time, Blanchard estimated a 3.0 percentage point drop in the ratio of consumption to US gross domestic product, a broad measure of economic output.