Pope Francis' role in Argentina's most famous case of priestly sex abuse is coming under renewed scrutiny as he faces the greatest crisis of his papacy over the Catholic Church's troubled legacy of cover-up and allegations he himself sided with the accused.

A police official in Buenos Aires province said officers seized documents from the archives of the Antonio Provolo Institute in the city of La Plata dating back more than 30 years.

A grassroots movement came closer than ever to achieving the decriminalization of the procedure in the homeland of Pope Francis.

Advocates of priestly abuse victims question how Francis could have been unaware of the allegations.