Several dozen conservative Catholic theologians, priests and academics have formally accused Pope Francis of spreading heresy with his 2016 opening to divorced and civilly remarried Catholics.
In a 25-page letter delivered to Francis last month and provided on Saturday to The Associated Press, the 62 signatories issued a "filial correction" to the Pope - a measure they said hadn't been employed since the 14th century.
The letter accused Francis of propagating seven heretical positions concerning marriage, moral life and the sacraments with his 2016 document "The Joy of Love" and subsequent "acts, words and omissions".
The initiative follows another formal act by four tradition-minded cardinals who wrote Francis last year asking him to clarify a series of questions, or "dubbia," they had about his 2016 text.
Francis hasn't responded to either initiative. The Vatican spokesman didn't immediately respond to an email seeking comment.
None of the signatories of the new letter is a cardinal, and the highest-ranking churchman listed is actually someone whose organisation has no legal standing in the Catholic Church: Bishop Bernard Fellay, superior of the breakaway Society of St Pius X. Several other signatories are well-known admirers of the old Latin Mass which Fellay's followers celebrate.
But organisers said the initiative was nevertheless significant and a sign of the concern among a certain contingent of academics and pastors over Francis' positions, which they said posed a danger to the faithful.
"There is a role for theologians and philosophers to explain to people the church's teaching, to correct misunderstandings," said Joseph Shaw, a spokesman for the initiative, signatory of the correction and senior research fellow in moral philosophy at Oxford University.
When it was released in April 2016, "The Joy of Love" immediately sparked controversy because it opened the door to letting civilly remarried Catholics receive Communion. Church teaching holds that unless these Catholics obtain an annulment - a church decree that their first marriage was invalid - they cannot receive the sacraments, since they are seen as committing adultery.