It is understood the WPP media agency is defending the business, which it won five years ago from Dentsu Aegis-owned Vizeum when Coke's media spend was in the region of £30m.
The review, which is at an early stage, puts into play duties on big brands including Coke, Diet Coke, Sprite, Fanta, Oasis and Schweppes.
Whichever agency walks away with the account could benefit from additional business in future should Costa Coffee join the Coca-Cola stable of brands. The drinks giant is in the process of buying the coffee brand from Whitbread in a £3.9bn deal announced on 31 August.
Costa’s media planning and buying account has been held by Publicis Groupe’s Zenith since 2009 and the relationship survived a competitive review earlier this year.
A spokesperson at Coca-Cola GB said: "We work with a range of different agencies across our business and brands. It is standard practice to review the agencies we work with on a regular basis."