McCann Erickson, which handled Heinz's tomato ketchup, baked beans and salad cream brands, claimed it resigned the account because of growing conflicts of interests with other clients.
Insiders claim the agency was forced to resign the business as it also works with Premier Foods. Heinz's rivalry with Premier has grown since the latter launched Branston Beans in 2005. Premier has pledged to spend £4m on marketing the product this year and is introducing an Omega-3 variant next week.
Heinz hired McCann Erickson following a protracted review that began a year ago, involving Abbott Mead Vickers BBDO and Beattie McGuinness Bungay.
Initially, it had planned to consolidate its advertising into one of its roster agencies, Leo Burnett, WCRS or BMB. However, the arrival of chief marketing officer Suzanne Douglas resulted in the pitch being expanded to include McCann Erickson, AMV BBDO and M&C Saatchi.