The move comes after the decision to award the Abbey National creative account to TBWA/London following a quick-fire review process.
Carat, the Abbey National media agency, is expected to be asked to repitch against agencies including Initiative Media, MindShare and Manning Gottlieb OMD. The agency handles media both for the main Abbey National brand and its internet bank Cahoot!, which spends £5 million on advertising.
The decision to review media follows reports that have suggested Abbey National is to rebrand as The Abbey after a brand review commissioned by Wolff Olins.
An Abbey National spokeswoman said: "We are carrying out a review of our brand using Wolff Olins and we hired TBWA for creative, so this review is a natural part of this process. We'll make a decision quickly as we don't see the point of drawing things out."
Carat is the long-standing incumbent on the business. The last threat to its hold on the account came in 1996 when Zenith Media appeared to have won a £10 million brief to work on the launch of a general insurance product, but the decision was reversed.
Earlier this year Abbey National, the UK's sixth-largest bank, announced losses of close to £1 billion.