The company is understood to have spoken to a number of agencies as part of a pitch being run from its head office in Switzerland.
Saatchi & Saatchi London, which has worked on digital campaigns for the company as part of its above-the-line relationship, is understood to have declined to pitch.
Cereal Partners UK has raised its spend on digital marketing over the past few years. It has used glue London to produce a microsite for Shreddies as part of the "school fuel for kids" positioning created by McCann Erickson, another of its above-the-line roster shops.
The review comes as Cereal Partners, a joint venture between General Mills and Nestle that markets breakfast cereals outside the US, is conducting a worldwide overhaul of its agency relationships.
At the end of last year, the UK division moved its Cheerios account out of Saatchis into McCann Erickson.
At the same time, Saatchis was handed a global brand advertising role for Cereal Partners' child-oriented products. The agency already handled brands including Honey Nut Cheerios, Cookie Crisp and Honey Stars.