The move means the battle for P&O Princess is nearly over. Shareholders of both firms will be asked to give the deal their blessing in March.

P&O had originally aimed to merge with its smaller US rival, Royal Caribbean.

Carnival's rival bid was at first rejected, but P&O switched sides last year when US and European competition regulators cleared both deals.

Carnival's agreement to run the new firm as a dual-listed company also helped to persuade P&O.

The dual listing means the two firms will retain their separate stock market listings, but will have one management.