The Minister for Public Enterprise, Ms O'Rourke, and the former minister, Mr Michael Lowry TD, will be called to an Oireachtas inquiry into a CI╔ rail signalling system. The inquiry, which opens on Monday, was established to find out why the estimated cost of the stalled project rose to £50 million from £14 million.

That rise has been linked to parallel work on a telecoms system built on the railway for Esat Telecom, which won the State's second mobile phone licence when Mr Lowry was Minister for Transport, Energy and Communications.

He and Ms O'Rourke are among 122 senior figures told by a subcommittee of the Oireachtas Joint Committee on Public Enterprise and Transport that they will be called to give evidence before the inquiry.

They include the some of the State's most senior Civil Servants and the former chairman of Esat Telecom, Mr Denis O'Brien, and its former acting chief executive, Mr Leslie Buckley, and a former Esat director, Mr Pβdraig ╙ hUig∅nn. Mr ╙ hUig∅nn is also a retired secretary general at the Department of An Taoiseach.

Another former minister at Ms O'Rourke's Department, Mr Alan Dukes TD, will also be called.

Among the Civil Servants to be called will be the Secretary General of the Department of Finance, Mr John Hurley, and his counterpart at the Department of Public Enterprise, Mr Brendan Touhy.

Mr Touhy is expected to be among the first to be called next week. The inquiry is also expected to call his predecessor, Mr John Loughrey and a CI╔'s former chief executive, Mr Noel Kennedy, on Monday.

The group's chairman, Dr John Lynch, and finance director, Mr Jim Cullen, are also expected to be called early next week.

In addition, the inquiry signalled it will call former executives at CI╔'s joint contractor, Modern Networks Ltd (MNL), which went into liquidation last month.

They include MNL's founder, Mr Jay Murray, and four former staff at CI╔'s rail subsidiary, Iarnr≤d ╔ireann, who left the State company to join it.

They are: Mr Brian Powell; Ms Mary Hand; Mr Bernard Kernan; and Mr Pat Judge. The inquiry also wants to call MNL's former chairman, Mr Pat Lynch, who joined the company after he ceased to be a non-executive director of CI╔ and Iarnr≤d ╔ireann.

He was also chairman of the State training and jobs authority, F┴S, at that time.

In a statement yesterday, the inquiry's chairman, Mr Seβn Doherty TD, said "materials of considerable and serious concern" had arisen in relation to the rail signalling system, known as Mini-CTC.

He said he did not know if certain figures were planning a legal challenge to the hearings.

Of the links between the Esat system and the rail signalling initiative, which is incomplete, Mr Doherty said rail safety may have been compromised. He added: "There has also been that while the two projects were to be progressed side by side, the Esat cable-laying took precedence and that this caused difficulties and added to the cost of the Mini-CTC."

Mr Doherty said the subcommittee had drawn no conclusions from its preliminary investigations.

Its members are: Mr Pat Rabbittee TD, Mr Jim Higgins TD, Mr Noel O'Flynn TD, Mr Martin Brady TD and Mr Austin Currie TD.

The hearings are scheduled to continue for four weeks - in the form of the DIRT inquiry two years ago - although Mr Doherty accepted it would not finish in that period.

The inquiry will be televised at morning time on Monday-Friday on TG4 and on Monday and Thursday afternoons on RT╔1.