VATICAN CITY — A top Vatican cardinal issued a scathing rebuke Sunday of the ambassador who accused Pope Francis of covering up the sexual misconduct of a prominent American cardinal, saying his claims were a "blasphemous" political hit job.

Six weeks after Archbishop Carlo Maria Vigano threw the papacy into turmoil over his claims about ex-Cardinal Theodore McCarrick, the head of the Vatican's bishops office said there was no evidence in his files backing Vigano's claims that Francis annulled any sanctions against McCarrick.

Cardinal Marc Ouellet's letter was issued Sunday, a day after Francis authorized a "thorough study" of all Vatican archives into how McCarrick rose through the ranks of the Catholic Church despite allegations he sexually preyed on seminarians and young priests.

The letter, addressed to Vigano but identified as an open letter to the faithful, marked an extraordinary end to the official Vatican silence about Vigano's claims. In it, Ouellet both defended the pope and excoriated Vigano, asserting that the conservative cleric had used the scandal over sexual abuse in the U.S. to score ideological points with Francis' critics on the Catholic right.

"In response to your unjust and unjustified attack, dear Vigano, I conclude that your accusation is a political setup without any real foundation that could incriminate the pope, and I repeat that it has profoundly wounded the communion of the church," Ouellet wrote.

Ouellet said a review of his files showed there were no documents about any sanctions ever imposed on McCarrick by former popes and that it was "false" to suggest Francis had annulled any such measures.

Ouellet did acknowledge that McCarrick had been "strongly exhorted" not to travel or appear in public, and to live a discreet life of prayer given rumors against him.

The McCarrick scandal has thrown the U.S. and Vatican hierarchy into turmoil, given it was apparently an open secret in some U.S. church circles that he would invite seminarians into his bed. Two men received settlements starting in 2005 from two New Jersey dioceses after they alleged McCarrick sexually molested or harassed them.

The Vatican was informed starting in at least 2000 about the seminarian complaints.

Francis accepted McCarrick's resignation as a cardinal in July after a U.S. church investigation determined that an allegation that he groped a teenage altar boy in the 1970s was credible. Since then, another man has come forward saying McCarrick molested him when he was a young teen and other men have said they were harassed by McCarrick as adult seminarians and priests.

Ouellet's letter marked the Vatican's first direct response to Vigano's 11-page denunciation Aug. 26 in which he accused two dozen Vatican and U.S. church officials of covering up for McCarrick, and demanded Francis resign for his role in the scandal.

Vigano claimed he told Francis during a June 23, 2013 meeting that Pope Benedict XVI had sanctioned McCarrick to a lifetime of penance and prayer for having "corrupted a generation of seminarians and priests."

Vigano implied that Francis still rehabilitated McCarrick from the "canonical sanctions" and made him a trusted counselor.

Ouellet, however, noted that the June 23 meeting occurred as Francis was meeting with all his ambassadors for the first time and was gathering an "enormous quantity of verbal and written information" about the church.

"I strongly doubt that McCarrick concerned him to the degree you'd like to think, given he was an 82-year-old emeritus archbishop who had been out of a job for seven years," Ouellet wrote.

Ouellet said in all his meetings with Francis about bishop nominations, he never heard him refer once to McCarrick as a trusted counselor. He said he couldn't believe Vigano had arrived at such a "monstrous" and "blasphemous" conclusion, given that Francis had nothing to do with McCarrick's career rise.

He said he understood that Vigano might be bitter at the way his own career ended and his disagreement with Francis' policies. But he wrote:

"You cannot end your priestly life in an open and scandalous rebellion that inflicts a painful wound" on the church and divides its people.

He urged Vigano: "Come out of your hiding place, repent for your revolt and return to better sentiments toward the Holy Father."