MIAMI, March 21 (Reuters) – US cruise companies are eager to add Cuba to their itineraries; but even if US policy allowed that, Cuba's ports would need years of rebuilding to accommodate the ships, industry officials said.

''Our business has grown so much that these ports in Cuba that were (established) in the time of the Spanish conquistadors, that size of ports, they're going to need a lot of infrastructure improvement,'' John Tercek, vice president of commercial development for Miami-based Royal Caribbean Cruises Ltd, said at an industry conference in Miami.

The world's three largest cruise companies – Carnival Corp. & Plc, Royal Caribbean and Norwegian Cruise Line, which is owned by US private equity firms Apollo Management LP and TPG Capital LP and by Genting Hong Kong Ltd. – are all headquartered in Miami. They are prohibited by the United States from doing business with nearby communist Cuba, under a policy aimed at depriving Cuba of US dollars until it adopts democracy.

The Caribbean region is the top destination for cruise lines because of its year-round mild weather and its proximity to North America, which is the source of more than 70 percent of all cruise passengers globally.

The cruise industry in turn pumped $2.27 billion into the economies of 29 Caribbean destinations last year, according to the Florida-Caribbean Cruise Association.

When industry officials gather each year at the Cruise Shipping Miami conference, the conversation inevitably turns to when US-Cuba relations might thaw enough for US-operated ships to call on Cuban ports.