ESAT founder Mr Denis O'Brien is among those expected to be called to give evidence to an Oireachtas inquiry into cost overruns on a new signalling system at Iarnrod Eireann. His associate, Mr Leslie Buckley, is also likely to be called.

The inquiry by a subcommittee of the Oireachtas Joint Committee on Public Enterprise and Transport is seeking to establish why the signalling system may ultimately cost £50 million (#63.5 million) despite an initial projection of £14 million.

A preliminary hearing last week heard that a project to build a parallel telecoms network for Esat group was linked to the signalling initiative from its inception.

Mr O'Brien and Mr Buckley struck the deal for Esat in May 1997. The subcommittee heard that Mr Buckley, then Esat's acting chief executive, had led its negotiation with CIE. He had worked as a consultant for CIE in the previous year.

Chaired by Mr Sean Doherty TD, the inquiry is also expected to hear evidence from CIE's then chairman, Mr Brian Joyce, and its then head of programmes and projects, Dr Ray Byrne.

In his opening statement last Wednesday, Mr Doherty acknowledged the assistance given to the Committee at an earlier stage by the late Mr Michael McDonnell, who was CIE group chief executive at the time of the project. After that hearing, Mr McDonnell's family sought legal representation to the inquiry.

The subcommittee is also considered likely to call civil servants who worked in the Department of Public Enterprise when the project was commenced.

Senior Iarnrod Eireann figures who left the State company to join its signalling contractor, Modern Networks Ltd, are also considered likely to be called.