MetroLink construction works are under investigation by the Public Accounts Committee after concerns were raised around spending procedures.
The PAC is investigating whether there was a tendering and procurement process carried out on already begun works at Grand Parade in Ranelagh.
The €12.5 million foundation construction for the proposed Charlemont stop of the underground rail system began a number of weeks ago.
International investment firm Hines are building the "enabling works" under a condition in a planning permission granted to them to develop the former Irish Nationwide Building Society's headquarters on Grand Parade.
Read more: €12.5 million Charlemont MetroLink works started without due process, says Councillor
Transport Infrastructure Ireland and the National Transport Authority both told Dublin Live the platform foundations were being built by Hines under an "agreement" reached between the three parties, whereby Hines would be paid the €12.5 million in tax payers money after the job was completed.
However, evidence of tendering and procurement processes, which ensure the best deal for State funds and competency of the client, were not provided by TII or the NTA when requested by Dublin Live.
There are also concerns over whether the planning permission is valid given a Railway Order is needed to construct rail infrastructure - which the MetroLink has not been granted.
Independent Councillor Mannix Flynn is understood to be seeking legal advice about taking a legal challenge which may halt the works.
Vice-Chair of the Public Accounts Committee Catherine Murphy said the spending watchdog agreed to investigate the issue on foot of Dublin Live's report.
She said: "There is a letter going from the Public Accounts Committee, specifically around that [issue] and the article, and hopefully we will get a reply to clarify just what exactly what is going on here.
"One of the things that is essential is that you would have robust tendering and procurement process. It is one of the issues that is at the very top of the agenda of the Public Accounts Committee because if you don't have a good process often you have a poor outcome.
She added: "Even in terms of value for money, it is essential that you have proper tendering process and in fact you are required to under the public spending codes."
Councillor Flynn, who originally raised concerns about the issue, urged the Minister for Transport Eamon Ryan to make a statement on the situation and warned the building works could be stopped by a court order.
He said: "The Minister for Transport should make a statement in relation to this situation bearing in mind that there is no railway order in place that would give this some measure of protection.
"This is wide open to a judicial review and a challenge in the courts. We thought we left the best part of these planning irregularities behind us.
"You could halt these works with a court order. If you were to judicial review this, you would laugh your way out of the court with all your costs paid.
"It is simply outrageous," he added.
Dublin Live has contacted Dublin City Council, the NTA and TII about the issues raised in this article but a response was not issued at time of publication.
Read more: South Dublin residents call for MetroLink terminus to be relocated to Cathal Brugha Barracks
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