John Lipsky, the number two official at the International Monetary Fund, said on Thursday he will step down from his post when his term expires at the end of August.

The IMF said Lipsky had agreed, at the request of IMF Managing Director Dominique Strauss-Kahn, to remain as a special advisor through the Group of 20 summit of rich and developing nations to be held in November.

Lipsky, whose official title is first deputy managing direction, was appointed to a five-year term in September 2006 after a long career in banking.

Most recently, Lipsky was vice chairman of the JP Morgan Investment Bank, having previously worked as the Wall Street giant's chief economist.

Strauss-Kahn, described Lipsky in a statement as an instigator of debate, an influential proponent of multilateralism and deeper financial surveillance, and an outstanding communicator