The energy giant has approached agencies to submit RFIs by next week, with the incumbent expected to repitch for the business.
It is understood that the media review does not affect Shell’s creative agency, JWT, or its digital agencies, AKQA and Proximity.
Shell has gradually consolidated its business into MediaCom, which handles the £7 million UK business.
Previously, the business was split between MediaCom and its WPP sister agency Maxus, but last year Shell moved accounts in markets such as India and Singapore out of Maxus and into MediaCom.
The two agencies won the business in 2005 when they pitched under a "Team Media for Shell" proposition, though the lead task was handed to MediaCom’s London office. Before that, Shell maintained a broad roster of agencies including MediaCom, Maxus, Initiative and Mindshare.