Ryanair will start feeding passengers to Norwegian Air Shuttle from airports including Dublin, Cork and Belfast, according to chief executive Michael O'Leary.
Mr O'Leary said Ryanair and Norwegian had reached an "agreement in principle" that will see the Irish carrier feed into the Scandinavian airline's long-haul operations out of London Gatwick. It serves a number of US destinations from the airport.
The two airlines have already begun working on aligning their booking systems to provide the feeder service.
Norwegian's Irish subsidiary, Norwegian Air International, is poised to receive a controversial permit that will allow it to commence flights from Cork to Boston this summer.
Last week, Mr O'Leary told the Irish Independent that Ryanair also plans to trial so-called interlining services between its own flights at Stansted and Barcelona later this summer. That will see passengers being able to transfer from one Ryanair flight to another while remaining airside. That means they won't have to check in their bags again or clear security a second time before boarding their next Ryanair flight.
The deal with Norwegian would be another transformative step for Ryanair. Mr O'Leary has said on a number of occasions that he thinks Ryanair will eventually become a feeder airline for legacy carriers such as Lufthansa as those airlines pare back their short-haul networks.
A shift to an operating model that includes lining up with long-distance routes is an "inevitable development," Mr O'Leary told Bloomberg yesterday. Transfers to established long-haul airlines could account for about 5pc of Ryanair's traffic by 2021, he said.