Arnold, who joined the agency last year, runs a department of ten teams that has picked up awards for work including the Army and Monster.co.uk. An agency insider described the split as "amicable".
However, it is thought that Saatchis has raised questions over the direction of the department under Arnold. It recently appointed the CDP creative Anthony Abdool as its joint deputy integrated creative director.
Arnold, who reported to the executive creative director, Dave Droga, joined Saatchis from Stretch the Horizon, where he was the creative
Saatchis hoped that Arnold would have a quick impact on its below-the-line offering. Droga said last June: "Chris has a very simple mandate; to make Saatchis dominant in the below-the-line arena overnight."
Arnold denied that he is leaving. He said: "I'm still here and there are plenty of exciting things going on."
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