By Tracy Rucinski

SEOUL (Reuters) - JetBlue Airways Corp is in discussions with Airbus SE about the European planemaker's plans for a longer-range version of its A321neo family as it prepares to jump into the transatlantic market, Chief Executive Robin Hayes said on Monday.

The sixth-largest U.S. carrier has 85 A321neo aircraft on order, of which it has already decided to convert 13 into a longer-range version called the A321LR for its planned launch of daily flights from New York and Boston to London in 2021.

But if the low-cost carrier decides to fly to other European cities such as Brussels or Amsterdam, it will need a plane with more stamina. It is studying the A321XLR, which Airbus has been promoting ahead of a formal product announcement in June.

"London is the biggest opportunity because it has the highest fares, but there would be other opportunities if we had an airplane that had more range. The XLR gives us more range," Hayes said on the sidelines of a global airlines meeting in Seoul.

"We're still working through how many aircraft it would be (but) any XLRs would be linked to the planes we have on order today," he told Reuters in an interview, adding any purchases would be converted from existing orders rather than generating completely new ones. No decision has yet been taken.

JetBlue is betting on its Mint business class product for narrowbody aircraft to succeed in the highly competitive premium transatlantic market. As of now, its U.S. customers have to fly to London on rival carriers where business class seats can cost as much as $12,000.

In the United States, JetBlue has argued that its Mint seats have driven a 50 percent decline in premium fares on some competing routes, and by sticking with narrowbody jets Hayes believes seats will be full.

U.S. carriers like American Airlines Group Inc and United Airlines service London with widebody aircraft that Hayes said can be tough to fill during off-peak travel.

"The transatlantic market is very seasonal. In the summer you tend to do very well but in the winter you're flying a bunch of empty seats, so the LR helps us manage significantly the risk of the winter because we're not flying such an expensive airplane."

A handful of Europe-based budget carriers have tried to penetrate the transatlantic market in recent years, but only cash-strapped Norwegian Air is still standing.

Hayes said he expects to work on code-share agreements with partners that have a strong presence in Europe, where the airline wants to eventually build up its brand.

A number of JetBlue's 50 airline partners have already reached out, he said.

(Reporting by Tracy Rucinski; Editing by Tim Hepher, Christopher Cushing)