Pope Leo XIV (C) greets the people after presiding over a meeting June 7 in Madrid, Spain, 07 June 2026. An arch-conservative Catholic group on Wednesday consecrated four bishops without the pope's permission and despite his appeal to them. Photo by Fernando Villar/EPA

July 1 (UPI) -- The Society of St. Pius X, a traditionalist Catholic organization, consecrated four bishops in a highly ritualized ceremony Wednesday without the consent of Pope Leo XIV.

The pontiff issued a last-minute appeal to the group to "desist from your intended act" and a warning that the ordination was "a sin of extreme gravity," The New York Times reported. The Vatican also said the bishops would be excommunicated if they went ahead with the ceremony.

Two of the men were from the United States, with one from France and one from Switzerland, The Guardian reported. The ceremony took place in Écône, Switzerland, where the SSPX started in 1970. The founders created the society to oppose what they considered liberalizing changes in the Catholic Church.

The SSPX rejects the decisions of the Second Vatican Council of the 1960s, which included allowing services in languages other than Latin. It is also against efforts to heal divisions between Catholicism and other forms of Christianity but considers the Roman Catholic Church to be the preeminent church of the world even as it criticizes modernization attempts as heresy.