Duff, who joined IPG in February 2006 as the president of Universal McCann in Europe and was then promoted to the wider Mediabrands role in January 2008, will leave Mediabrands at the end of the month.
Nick Brien, the global president and chief executive of Mediabrands, is now looking for a successor to Duff to be in place during the first quarter of 2010.
Brien said that Mediabrands, which incorporates IPG media companies including Universal McCann and Initiative, is looking for a European leader to achieve greater external focus on business model reinvention.
Under Duff, Mediabrands appointed Jim Hytner as EMEA president of Universal McCann.
Duff said: For the past few weeks, Nick and I have been discussing how the role should evolve. But, ultimately, we have a difference of opinion.
"It is therefore sensible that I should move on.
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