The proposal is thought to be the work of the new European head of credit cards, Alan Silverman, who joined Citibank last month from Barclays. Discussions are in their early stages.
The launch will not affect Citibank's corporate above-the-line advertising business, handled by Fallon. Wunderman handles direct marketing across Europe.
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The US-owned bank is the world's biggest issuer of credit cards and already has a number of them in the UK. It recently launched a product called Citibest - an all-inclusive current, savings and credit card and investment account.
Competition is likely to increase in the credit card market this year with Citibank rivals plotting further launches.
Citibank has launched a number of targeted credit cards in other parts of the world. Last year it launched a card aimed at young urban professionals in Malaysia.
Silverman was travelling and not available to comment. However, a Citibank spokeswoman denied the group was planning to launch another credit card.
But she added: "As a large company we're always reviewing our agency capabilities."