It is understood that Eccleshare's role at BBDO will now be restructured, with internal appointees taking on his responsibilities.
In the newly created role, Eccleshare will run all of Clear Channel International's businesses, including poster, radio and other media interests, outside of the US. All country and regional heads at Clear Channel will report to Eccleshare. He is expected to take up his position in September.
The hiring was driven by the private equity buyers Bain Capital and Thomas H Lee, which own 90 per cent of Clear Channel. Eccleshare will have an equity stake in the business as part of the appointment.
Eccleshare said: "It's hard to leave Campaign's Network of the Year. However, the Clear Channel role is simply too good to miss."