German daily FAZ (Frankfurter Allgemeine Zeitung) reported that the cruise company would order an additional ship from Finnish shipbuilder Meyer Turku for about EUR 500 million (US$614 million).
The TUI spokesman added the purchase would be financed in a similar way as previous orders, with around 80% debt-financed and 20% covered by its own funds.
The newbuild will be about the same size as a couple of ships TUI already has on order. Those are due to be delivered in 2018 and 2019 and each will have capacity of about 2,900 guests.
Those two liners will replace smaller ships in the existing fleet of TUI Cruises, though FAZ said the line could hold off retiring Mein Schiff 2 to keep up with rising cruise demand.