All 34 Chilean bishops who attended a crisis meeting this week with Pope Francis about the cover-up of sexual abuse in their country have offered to resign, the bishops said in a statement released on Friday.

It was not immediately clear if the pope would accept all or any of the resignations.

"We have put our positions in the hands of the Holy Father and will leave it to him to decide freely for each of us," the bishops said in their statement, in which they also apologised to Chile, the victims of abuse and the pope for the scandal.

The scandal has devastated the credibility of the Church in the once staunchly Catholic country. It has also hurt the pope's own image because this year he strongly defended a bishop accused in the alleged cover-up before reversing his position.

This week's meeting followed a Vatican investigation into Bishop Juan Barros, who was appointed by the pope in 2015 despite allegations that he had covered up sexual abuse of minors by his mentor, Father Fernando Karadima.

Now 87 and living in a nursing home in Chile, Karadima has always denied the allegations. Barros has said he was unaware of any wrongdoing.

However, the Vatican confirmed on Friday Chilean media reports that the pope had handed the bishops this week a document accusing them of destroying evidence of sex crimes and of failing to protect children from predator priests.

Read: Pope set to be blunt with Chile bishops to unravel abuse cover-up

In a dramatic U-turn, Pope Francis's letter said that he had made "grave mistakes" in the handling of the sexual abuse crisis because he had been misinformed.

The letter followed a Vatican investigation into Bishop Juan Barros, who was appointed by the Pope in 2015 despite allegations that he had covered up sexual abuse of minors by his mentor, Father Fernando Karadima. Bishop Barros has said he was unaware of any wrongdoing.

The investigation was carried out by Maltese Archbishop Charles Scicluna.