VATICAN CITY: The Vatican said on May 13 that a breakaway Catholic group that supports the old Latin Mass should cancel its plan to appoint new bishops without Pope Leo's approval.

It warned that doing so would lead to excommunication from the 1.4-billion-member Church.

This is the first time during Pope Leo's leadership that the Church has threatened its most severe punishment. The Vatican office in charge of doctrine told the Switzerland-based Society of St. Pius X that appointing bishops without permission would cause a "schism," meaning a formal break from the pope.

Cardinal Victor Fernandez said such a ceremony would be a serious offense against God and would result in excommunication.

The Society of St. Pius X is a very traditional group that rejects key teachings from the Second Vatican Council, a major meeting in the 1960s that introduced reforms in the Church. One of those changes allowed Mass to be celebrated in local languages rather than only in Latin, which the group opposes because it prefers the traditional Latin form.

People who are excommunicated are completely cut off from the Church. They cannot receive sacraments or hold Church positions unless they repent. If they die while excommunicated, they are not given a Catholic burial.

The group has had difficult relations with the Vatican for many years. Its founder, Archbishop Marcel Lefebvre, was excommunicated in 1988 after appointing bishops without permission from Pope John Paul II. Later, Pope Benedict XVI tried to improve relations and removed the remaining excommunications.

In February, the group's current leaders said they plan to appoint new bishops in July without Vatican approval, saying they need more leaders.

However, the Church strictly teaches that only the pope can approve the appointment of new bishops to maintain a direct link to Jesus' 12 apostles. If bishops are appointed without the pope's permission, both the person being appointed and the one conducting the ceremony are automatically excommunicated.