Josef Wesolowski was placed under house arrest earlier this week after he was formally charged by Vatican police.
The Holy See has now confirmed the nature of the charges he faces, including one of having child porn.
Wesolowski was the former Vatican ambassador to the Dominican Republic and an archbishop in the country before being defrocked when a Church tribunal found him guilty of abusing young boys.
Vatican spokesman Father Federico Lombardi said Wesolowski had be placed under house arrest because he was a flight risk and it was feared he might tamper with evidence.
It is thought his trial could take months.