The brief is believed to include all consumer-facing PR on its entire confectionery range - currently split between Jackie Cooper PR and Ketchum.
Mars owns Snickers, Galaxy and Twix and industry insiders speculated the account was worth more than £500,000.
The firm has drawn up a shortlist that includes the incumbent agencies. PRWeek understands that Mars is not looking to replace JCPR and Ketchum on its pet-care or wider food brands such as Uncle Ben's and Dolmio.
Mars recently brought in Freud Communications to handle public affairs and corporate PR.