An air of mystery has always prevailed over who exactly is a member of the organisation, with rumours of cabinet ministers, senior judges, solicitors and accountants all being linked to Opus Dei. And despite becoming more open in recent years, Opus Dei has never revealed the identities of its more high-profile Irish members.

In 2003, former education minister Michael Woods reacted angrily to a suggestion by former Labour minister Justin Keating that he brokered a deal beneficial to religious orders because he was a member of Opus Dei.

Branding the allegation "utter rubbish", Woods said, "I have been accused of being a member of Opus Dei because I am a Catholic? There have been numerous accusations over the years and I treat them all the same way, as absolute rubbish."

"Like dioceses and parishes, Opus Dei does not publish lay members' names, " said a spokesman for Opus Dei Ireland. "Neither do health clubs for that matter, and people surely deserve as much privacy in their spiritual affairs as they do in medical matters.

Members, however, are more than happy to tell you of their membership and what Opus Dei is all about."

Certainly a few well-known figures have been open about their involvement with the organisation. In 1992, High Court judge Justice Rory O'Hanlon revealed that he was a member of Opus Dei. A staunch pro-life and antidivorce campaigner, O'Hanlon died in 2002 and was survived by his 12 children.

Kildare stud manager Stan Cosgrove, part-owner of the racehorse Shergar, has been a member of Opus Dei for 40 years. In the past, he has said it helped him in his work in the racing business. "Opus Dei helps me to ensure that I do the job well and it also helps me to sanctify my professional, social and . . . above all . . . family life, " he said. Cosgrove has 10 children, none of whom are members of Opus Dei.

UCD lecturer Geraldine O'Connor has been linked with Opus Dei. O'Connor, a former lecturer in UCD, was involved in controversy in 2004 when it was claimed that she told students to attend an Opus Dei event in order to pass their exams.

Neil Dean, who was chief financial adviser of AIB until he retired in 1997, publisher Michael Adams, the head of Four Courts Press, and Noel Duff, former owner of Buswells Hotel in Dublin, are all members of Opus Dei.

Dean, a supernumerary, is head of famED (family education), which runs the Rockbrook and Rosemont Park schools in Dublin.

Last December, Adams, a numerary, was awarded an honorary degree at Trinity College in recognition of his contribution to academic publishing in the humanities.

Opus Dei's history in Ireland began with the ordaining of its first Irish priest in 1955.

Cormac Burke, a UCD graduate in modern languages from Sligo town, went on to become a judge of the Holy Roman Rota (the Vatican's supreme marriage tribunal) in 1986.

Other early members of Opus Dei included Professor Seamus Timoney of Timoney Technology and Fr Richard Mulcahy (son of former army chief-of-staff General Patrick Mulcahy).

Fundraising events and official openings of Opus Dei centres were attended in the 1950s and '60s by such noteworthy figures as former taoisigh John A Costello, Eamon de Valera and Sean Lemass, as well as former President Cearbhail O Dalaigh. Seminars and retreats are organised regularly at Opus Dei's conference centres, at Lismullen, Co Meath and Ballyglunin, Co Galway, while media seminars are held every two years at Cleraun Study Centre in Dublin.

"All our conferences are geared at the values side of life, " said Michael Kirke of the Opus Dei Information Centre, Dublin. "Opus Dei has a big interest in the working side of life and we look at different areas where people can identify with work and connect with their spiritual side at the same time."

Past speakers at these seminars and conferences include justice minister Michael McDowell, information commissioner Emily O'Reilly, Leinster MEP Mairead McGuinness, chief executive of the Special Olympics, Mary Davis, Michelin-starred chef Richard Corrigan, and broadcasters Joe Duffy, Mary Wilson and Damien Kiberd.