Pope Francis has cracked down on the spread of the old Latin Mass, reversing one of Pope Benedict XVI's signature decisions in a major challenge to traditionalist Catholics.
Francis said he had reimposed restrictions on celebrating the Latin Mass that were relaxed in 2007 because Benedict's reform had become a source of division in the Roman Catholic Church and used as a tool by Catholics opposed to the Second Vatican Council, the 1960s meetings that modernised the church.
The pontiff issued a new law requiring individual bishops to approve celebrations of the old Mass, also called the Tridentine Mass, and requiring newly ordained priests to receive explicit permission to celebrate it from their bishops in consultation with the Vatican.
Under the new law, bishops must also determine if current groups of faithful attached to the old Mass accept Vatican II, which allowed for Mass to be celebrated in the vernacular rather than Latin. Bishops are no longer allowed to authorise the formation of any new pro-Latin Mass groups.
The move will create uproar among traditionalists already opposed to Francis's more progressive leanings and still nostalgic for Benedict's doctrinaire papacy.
Francis said he was taking action to promote unity and heal divisions within the church that had grown since Benedict's 2007 document, Summorum Pontificum, relaxed the restrictions on the old Mass.
Benedict took action in a bid to reach out to a breakaway group that celebrates the Latin Mass, the Society of St Pius X, which had split from Rome over the reforms of Vatican II.
But Francis said Benedict's effort to foster unity had essentially backfired.
In a letter to bishops accompanying the new law, Francis said the opportunity offered by Benedict was "exploited to widen the gaps, reinforce the divergences, and encourage disagreements that injure the Church, block her path, and expose her to the peril of division".
He said he was "saddened" that the use of the old Mass "is often characterised by a rejection not only of the liturgical reform, but of the Vatican Council II itself, claiming, with unfounded and unsustainable assertions, that it betrayed the Tradition and the 'true Church'".