General Mills UK - formerly Pillsbury UK - has handed the creative accounts for the Old El Paso and Green Giant brands to its roster agency Saatchi & Saatchi.
Leo Burnett's relationship with Kellogg is understood to be behind the split, following General Mills' acquisition of the Pillsbury foods business from Diageo last year. General Mills owns half of Cereal Partners, in a joint venture with Nestle and sees Kellogg as one of its key competitors.
It has also recently ended Pillsbury's partnership with Leo Burnett in the US for the same reason.
Saatchi & Saatchi is Cereal Partners' London agency for the Cheerios range, and sits alongside McCann-Erickson on the Cereal Partners roster.
Linda Hipkiss, GM's UK commercial director for ambient foods, said: "General Mills has several globally-aligned agencies and so it makes sense for us to move Green Giant and Old El Paso business to one of them. Pillsbury also owns Bugles savoury snacks and Betty Crocker cake mixes. Ads for Bugles are created by McCann-Erickson.
The company uses different agencies for its frozen and chilled brands, which are overseen by commercial director Mark Lloyd in the UK. General Mills recently handed the advertising brief for Haagen-Dazs ice cream to TBWA/London.
In May, the company unveiled its biggest UK marketing splash yet for Old El Paso, a £6m, three-month TV campaign by Leo Burnett, with two executions showing how and when to eat Mexican food.
Leo Burnett was also behind the return of the jolly green giant in September 2000, with a 30-second TV spot in which the animated giant reached into the sky to wring out the clouds and point the sun down at his crops. The last time he appeared on TV in the UK was at the end of 2001.
Hipkiss said the giant would continue to be the face of the Green Giant brand, the UK's market leader in tinned sweetcorn. "The green giant is a brand icon and he is fantastically powerful, she said. But she refused to say when the brand would return to TV.