ROME — The Vatican has decided to fight fire and brimstone with fire and brimstone.

Six weeks after Archbishop Carlo Maria Viganò, the former Vatican ambassador in the United States, shook the church by accusing Pope Francis of covering up sexual abuse, the Vatican broke its public silence on Sunday with a scathing public retort from a powerful prefect for the Congregation for Bishops.

The prefect, Cardinal Marc Ouellet, called the accusations by “dear Viganò” “false,” “far-fetched,” “blasphemous,” “incomprehensible,” “abhorrent” and politically motivated to hurt Francis. He suggested that the archbishop would be wise to “quickly repair” his break with the pope.

“I cannot begin to understand how you let yourself be convinced of this monstrous accusation, which does not stand up,” Cardinal Ouellet said in the letter, which was written in French.

Archbishop Viganò did not immediately return a request for comment on Sunday.

On Aug. 26, conservative Catholic outlets critical of the pope published a long letter by the archbishop accusing Francis of lifting punishments for sexual misconduct for a former American cardinal, Theodore McCarrick, that were reportedly imposed by Pope Benedict XVI.