The Society of St. Pius X said its governing council expelled Bishop Richard Williamson because he ignored a deadline to "declare his submission" to its authority and had called for the society's superior to resign.
A spokesman for the group said Williamson's comments about the Holocaust were part of the reason for his expulsion.
In a 2009 interview with Swedish TV, Williamson denied that any Jews were killed in Nazi gas chambers.
The comments earned him a criminal prosecution in Germany, where Holocaust denial is a crime, and caused great embarrassment to German-born Pope Benedict XVI, who had lifted Williamson's excommunication from the Church on the day the interview was broadcast.
But Williamson also angered the group's superiors by posting attacks against them on a blog that was "full of crude ideas" and by performing sacraments despite being forbidden to do so, said the spokesman, Andreas Steiner. "The third thing, which was key, was that he always criticized the talks with Rome (the Vatican)," Steiner told The Associated Press.
The Society of St. Pius X was founded in 1969, opposed to the reforms of the Second Vatican Council. In 1988, the Vatican excommunicated the group's founder and four bishops—including Williamson—after he consecrated them without papal consent.