It is due to hold a pitch later this year and follows a review of the existing framework led by Douglas McArthur, founder of the Radio Advertising Bureau (RAB).
Incumbents on the roster are Carat, Starcom, Mediacom, digital agency i-Level and outdoor company Posterscope.
The move to consolidate the media buying function has been made in response to the changing media marketplace and the growth of digital media.
COI deputy chief executive Peter Buchanan says: “COI is currently in consultation with clients on how we best configure our media buying contracts to meet their needs and reflect the marketplace. We will make a formal announcement shortly.”
The latest development comes as the COI revealed this week (20 July) that Government marketing and communications spend has jumped by almost half to £540m.
Issues such as obesity, smoking, climate change and the recession pushed spending up 43% year on year in the 12 months to the end of March.
In response, the Conservative Party has again slammed Government ad spending at a time of economic crisis, standing by its promise that it would slash ad budgets under a government led by David Cameron.