Train passengers from Northern Ireland could be set to travel directly into Dublin Airport on a new €300m service planned by the Republic's rail operator, it can be revealed.
Irish Rail chief executive David Franks said attracting rail users from Northern Ireland would be a big part of the ambitious scheme.
But the plan has also sparked renewed calls for a direct rail link to Belfast International Airport, which could suffer if the proposal goes ahead.
Irish Rail is planning a new line to allow intercity trains to travel direct to Dublin airport from Cork, Galway and Belfast.
Dublin Airport is Ireland's biggest, offering 161 routes from 53 airlines. More than 21 million people used it last year, 570,000 of them from Northern Ireland.
The company suggested the line could cost €300m (£223m), but would open its entire rail network to air passengers and boost tourism.
"One of the biggest contributions we can make to the economy is moving people over long distances and into city centres fast," said Mr Franks.
"My vision is more a Manchester Airport connection where you can go all over the country using diesel trains. You could gain access to Cork, Galway or Belfast."
Irish Rail believes it could be built in less than five years, and carry three million airport passengers. But the line would risk pulling even more passengers towards Dublin and away from regional airports.
Last May, Stormont Regional Development Minister Danny Kennedy proposed a feasibility study for a new route to serve Belfast International Airport.
Last night, South Antrim MLA Danny Kinahan said Dublin's plans should concentrate minds here to ensure Belfast International Airport does not lose out.
He said he was "shocked but not surprised" at talk of a new line into Dublin Airport, but added: "Sadly from an Irish point of view it seems sensible, but we really need to look at how we help Belfast International Airport.
"We need to look at having an aviation strategy. It really needs to concentrate minds."
He said the economic viability of reopening the Knockmore-to-Antrim line close to Aldergrove needed to be examined, including a station for the airport with a bus link to the airfield.