P&O Cruises is understood to be holding a statutory review of its &£5.5m advertising account, held by Lowe Lintas.
The business was held by Ammirati Puris Lintas but moved across when APL and Lowe Howard-Spink merged late last year. Most of the advertising is press work.
It is not known whether P&O has contacted other agencies. No one at the company was available for comment.
The move comes in the same week that the ferry company announced it was demerging its cruise business – P&O and US operation Princess Cruises – to form a separate group. The new division will be listed on the New York and London stock markets by the end of the year.
The UK-based business operates four ships in European waters, including the Oriana. The company offers a range of winter cruises, including round-the-world trips and fly-cruises to the Caribbean.
Last week, P&O Stena Line unveiled plans to import cut-price cars on its European ferry routes, partly to offset the loss of earnings triggered by the scrapping of duty-free.
It is unclear whether the media account, held by Initiative, is affected by the review.