The Wrigley Company is active in more than 30 markets, including some 20 European territories. It is headquartered in the US, where it handed its £85m media planning and buying account to the WPP Group-owned MindShare in January, following a pitch involving its other roster agencies, WPP's MediaCom and Omnicom's OMD.
A Wrigley Company spokesman said: "This is only a statutory review, something all companies have to go through. We're very happy with the work MediaCom are doing."
MediaCom UK chief executive Nick Lawson said the UK portion of the business would not be affected by the review.
The agency's work for the Wrigley Company has included brokering Extra's multi-million pound sponsorship of teen drama Hollyoaks.
Last month the advertiser partnered with portal Yahoo! to make its online advertising debut in the UK. Part of Yahoo! Music, The Extra Venue has content including the Live and Up Close programme, which offers consumers the chance to attend intimate live shows or view them online, building on Extra's "Get a Little Closer" brand message.
The Wrigley Company's brands also include Airwaves, Hubba Bubba bubble gum and Wrigleys Juicy Fruit, Orbit and Spearmint. As well as MediaCom and its subsidiary MediaCom Outdoor, it works with the agencies Abbott Mead Vickers, Vibe and Bray Leino and Ideas Eurobrand.