New Delhi, July 3 -- The Vatican responded aggressively Thursday to a traditionalist group that consecrated bishops without the pope's consent, declaring the Society of St. Pius X had formally broken with the Catholic Church. It excommunicated its bishops and priests, and warned its faithful that they too face the harshest sanctions in the church.

By declaring a schism and extending excommunications to potentially thousands of Catholics, the Vatican's doctrine office went above and beyond the minimum sanctions foreseen by the church's canon law to respond to the consecrations Wednesday of four new bishops.

The society, known by its acronym SSPX, celebrates the ancient Latin Mass and opposes the modernizing reforms of the Catholic Church...