Metro West has been put on hold indefinitely after the Minister for Transport suspended the planning process.
Leo Varadkar said funding to construct the new railway will not be available for the foreseeable future.
In a statement, the Minister said until financial credibility is restored, the international debt funding market would be reluctant to lend funds to finance projects in Ireland, and the Exchequer will not be able to make its contribution to the cost in the foreseeable future.
Mr Varadkar said: "Acting on the advice of the National Transport Authority (NTA), I have instructed the Railway Procurement Agency to withdraw its application for a Railway Order from An Bord Pleanála".
He said Metro West has always been considered a long-term project and many of the new communities that it would serve have not materialised due to the collapse in home building.
However, Minister Varadkar did not rule out the project completely saying it will be examined again when the country’s finances have improved.
The Metro West line was due to go from Tallaght through Clondalkin, Liffey Valley and Blanchardstown, and link up with the planned Metro North line to end at the airport.
