Representatives of the special liquidator of IBRC served papers on three former directors of Irish Nationwide last night.
It is understood the legal action relates to their stewardship of the building society.
Papers were served on former directors Terence Cooney and Stan Purcell, and former chairman Michael Walsh.
It is understood that it is intended that papers will be served on former managing director Michael Fingleton and another former director David Brophy.
The development follows a step by IBRC to last year to take action against the directors of the building society.
The bank filed a plenary summons in the High Court last March so its legal action would not be constrained by time limits under the statute of limitations.
It was speculated the legal action related to alleged breach of contract, breach of fiduciary and breach of duty of care.