The handling of allegations of child sex abuse in Dublin was investigated
The inquiry into sex abuse by Catholic priests in Ireland has disclosed that the Vatican ignored formal requests for information.
The inquiry asked for details of reports on abuse sent to the Vatican by the Dublin archdiocese in 2006.
The Vatican did not reply but told the Irish Foreign Affairs department the request "had not gone through appropriate diplomatic channels".
The inquiry condemned church leaders for covering-up abuse for decades.
The Report of the Commission of Investigation into the Catholic Archdiocese of Dublin, which was published on Thursday, covered a period from 1975 to 2004.
The commission said it was independent of the government and therefore did not regard it as appropriate to use diplomatic channels when seeking information.
A request for information from the Papal Nuncio also was ignored.
In February 2007, the commission wrote to the Dublin-based Papal Nuncio asking him to forward all relevant documents in his possession.
It also requested that he confirm whether he had any such documents but the Papal Nuncio did not reply.
Earlier this year, the commission again failed to receive a reply after sending the Papal Nuncio extracts from its draft report which referred to him and his office, as it was required to do.
The Vatican told The Irish Times it "was a matter for the local church involved".
A senior Vatican spokesman said diplomatic practice required that outside requests made to the governance of the Vatican pass through diplomatic channels, in this case the Department of Foreign Affairs in Dublin and the Irish Embassy to the Holy See in Rome.
The leader of the Catholic Church in Ireland has said he is deeply sorry and ashamed by the child abuse the report had revealed.
Cardinal Sean Brady also apologised for the way the Church covered-up the crimes.
The report also found that on occasions senior police officers colluded in the cover-up.
The commissioner of the Irish police, Fachtna Murphy, apologised for the police failure to protect victims.
Victims groups are now calling for a similar inquiry to take place in every diocese in Ireland.
However, the Auxiliary Bishop of Dublin Eamonn Walsh has said he does not believe that should happen.
He said it would be better for the Church to use its "time, energy and money" to improve child protection measures.