The national rail transport pressure group, Platform 11, is opposing the reopening of the Western Rail Corridor (WRC) linking Sligo with Galway and Limerick.
The group maintains that the estimated €300 million it would cost to reopen and upgrade the link along a mostly disused line could be better spent on other rail projects, such as the Cork-Midleton, Dublin-Navan and Athlone-Mullingar lines.
The group's spokesman, Mr Derek Wheeler, said €300 million would go a long way towards securing the future of existing regional rail routes such as the Limerick-Waterford line.
Mr Wheeler said that Dublin remained the only capital city in the EU still without a rail link of any kind to its airport.
Platform 11, he added, did not believe that the WRC would deliver value for money to Irish taxpayers.
"Rail transport in the west of Ireland would benefit more from increasing the frequency of current services into the region, which would, by default, also create viable commuter services in the west and midlands."
He said there was no major population centre north of Tuam which was not currently served by rail.
Regarding road-traffic congestion, which may justify a WRC rail commuter service, he maintained that this currently exists only between Tuam and Galway city.
However, a spokesman for the West on Track campaign expressed surprise at the Platform 11 position.
He pointed out that the campaign to reopen the route was supported by three regional authorities and local-development and tourism groups.