A 1997 VATICAN directive rejected a recommendation by the Irish Catholic Church that priests who abused children should be reported to the civil authorities, it has emerged.

The disclosure is made in an RTÉ documentary to be broadcast tonight, which also reports that an Irish bishop described the Vatican directive as “a mandate . . . to conceal the reported crimes of a priest”.

The Would You Believedocumentary, Unspeakable Crimes, is broadcast on RTÉ One television at 10.35pm.

In a January 1997 letter to each Irish bishop, marked “strictly confidential”, the Vatican said it would support the appeal of any priest defrocked by the Irish church in connection with child sex abuse. It did so in a number of cases, leading to a threat of resignation by one Irish archbishop.

At a 1999 meeting in Rome the Irish hierarchy was reminded collectively by a top Vatican official that they were “bishops first, not policemen”.

The programme claims the Vatican and Pope Benedict himself failed to apply the norms of canon law to the issue of child abuse, one of the pope’s major criticisms of Ireland’s bishops. The Vatican failed to do so where two US priests were concerned and the pope did so in 2005 where Fr Marcial Maciel, founder of the Legionaries of Christ, was concerned.

In his letter to the Catholics of Ireland last March, Pope Benedict said to his “brother bishops’’ that “you and your predecessors failed, at times grievously, to apply the long-established norms of canon law to the crime of child abuse”.

The Vatican opposed a recommendation in the Irish Bishops’ “Green Book” guidelines on child protection, published in January 1996, which said all allegations of clerical child sex abuse should be reported to the civil authorities.

The programme, by reporter Mick Peelo, also shows a “strictly confidential” letter sent to Irish bishops by the Vatican a year later, in January 1997, which expressed “serious reservations of a canonical and moral nature” about the mandatory reporting of such crimes to civil authorities.

An Irish bishop confirmed to the programme, on condition of anonymity, that he made a note at the time describing this letter as “a mandate to conceal the crimes of a priest”.

The programme also reports that at a 1998 meeting with Cardinal Castrillón Hoyos, prefect of the Congregation for Clergy (1996 until 2006), then archbishop of Dublin Desmond Connell thumped a table in frustration as the cardinal insisted it was Vatican policy to defend the rights of an accused priest above all.

Last month, Archbishop of Dublin Diarmuid Martin said that, in the past “most of the Irish bishops felt that dealing with the Congregation for Clergy was disastrous”.