For example he opposed religious freedom, interreligious dialogue and collegiality among bishops. As a whole, the group is not in communion with the pope.
Fellay took part in a meeting with the Vatican last June. Both gruops have had ongoing communication since at least 2009.
That same year Benedict XVI revoked the excommunication of the four bishops who were illicitly ordained in 1988 by Marcel Lefebvre, but their status inside the Church remains unclear.
The Lefebvrites have 551 priests, 239 seminarians and roughly 100,000 followers worldwide.