The controversial MetroLink works which began before the underground rail system was granted planning permission are now under investigation by Dublin City Council.
The Public Accounts Committee, which monitors the spending of state funds, is also investigating whether the €12.5 million works went through tender and procurement processes, Dublin Live previously revealed.
The construction for the foundations for the proposed Charlemont stop of the underground rail system began a number of weeks ago despite the project not being granted a Railway Order.
Read more: MetroLink works under investigation by spending watchdog
International investment firm Hines are building the "enabling works" at a cost of €12.5 million under a condition in a planning permission granted to them to develop the former Irish Nationwide Building Society's headquarters on Grand Parade, in Ranelagh.
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.
Independent Councillor Mannix Flynn, who raised previously raised concerns about the validity of the planning, called for DCC's Chief Executive Owen Keegan to make a statement on the works in an emergency motion.
In a response, seen by Dublin Live, Lord Mayor Alison Gilliland confirmed that the Planning Enforcement Section of the Council will investigate the matter immediately.
She said: "The matter has been raised with the Assistant Chief Executive who confirms that the Planning Enforcement Section will open an enforcement file immediately and initiate an investigation into the matters raised in the Councillor's motion.
"Once an inspection has taken place and the facts relating to the works have been clarified the Councillor will receive a substantive response outlining whether the works concerned are exempted development, and if not the enforcement action proposed to deal with any unauthorised works concerned."
A spokesman for Hines previously said the firm "has acted fully in line with its planning permission and put in place the requite enabling works required for the site."
Previously, Dublin Live reported that over 1,000 South Dublin residents were calling for the final stop of the long-awaited MetroLink to be relocated from Charlemont to Cathal Brugha Barracks or St Stephen's Green.
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Read more: €12.5 million Charlemont MetroLink works started without due process, says Councillor
