Shine Communications, Porter Novelli and 20-year incumbent Counsel -- the firm's three UK-rostered firms -- were this week locked in discussions with the food giant over future PR strategy.
Heinz Europe director of corporate affairs Michael Mullen, who is co-ordinating the review, said: "We don't comment on rumours or speculation."
Shine and PN said Heinz had instructed them not to comment on the review, which, according to one of the agencies, has reached a "sensitive stage".
Counsel -- Heinz's retained agency for almost two decades -- did not return calls from PRWeek.
Heinz, which is expected to confirm a fresh agency line-up within a month, is to launch a range of potted snacks called Pasta Shakers and plans to boost its chilled-food ranges. The firm has already launched its Salad Shakers range.
It is also reportedly planning to launch low-carb versions of brands such as Baked Beanz and Salad Cream.
Heinz recently revamped its baked beans in the UK, attempting to promote a healthier image with an energetic "Superbean" character. It has relaunched its Classic and Big Soup ranges to cut sugar, salt and fat.
Heinz hired Edelman to handle PR in the US four months ago but the agency has had no discussions with Heinz over a UK contract.
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