In a statement, AOL UK said: "We evaluate suppliers on a regular basis and during 2003 we will be undertaking a standard assessment of our marketing agency needs."
AOL UK confirmed that this included the accounts held by MWO and BBJ, but that the company had "not formally started speaking to any agencies yet".
However, it is understood that agencies have submitted credentials, with further meetings expected to take place in the spring.
The ISP said it recently held a competitive review of the business held by its brand tracking research agency, Hall & Partners, which the incumbent managed to retain.
A spokeswoman for AOL UK added that the company "couldn't yet confirm what format the review (of MWO and BBJ) would take".
MWO is the agency behind the creation of the ubiquitous Connie character, which has been a stalwart of AOL's TV ads since September 1998. The agency has held the account for more than four years, having scooped it one month after AOL UK parted from its previous agency, Barrett Cernis, in August 1998.
BBJ picked up the planning and buying account several weeks later, after a four-way pitch in which the then incumbent, Mansfield Lang, did not repitch.
In September 2001, MWO spruced up Connie's image ahead of a cross-media campaign. Her new look featured make-up by the make-up artist Jemma Kidd and hair styled by Trevor Sorbie.
The move to review in the UK follows the announcement earlier this month that AOL in the US has dropped its New York-based agency Gotham, part of the Interpublic Group, after eight years.
The dismissal came after Leonard Short took the role of executive vice-president of brand marketing. In a prepared statement, AOL said that the company would best be served "exploring a new agency relationship".
Steve Case, the chairman of the beleaguered AOL Time Warner, has also agreed to step down in May, after months of shareholder pressure. Case founded America Online, which merged with Time Warner in 2000.
Since the merger, which was originally hailed as a cutting-edge deal that would unite the cream of new media and old media, shares in AOL Time Warner have lost about 70 per cent of their value.