Chilean bishops summoned to the Vatican to discuss the abuse crisis have spent 24 hours in retreat at the request of Pope Francis, praying and reflecting on specific themes, ahead of their meeting with the pope today.

Pope Francis met with the Chilean bishops yesterday afternoon before meetings again today and tomorrow.

Francis gave the bishops a text 'with different themes for meditation' the Vatican said. Those themes have not been made public, the Catholic News Agency (CNA) reported.

It is now known whether Pope Francis will also hold private audiences with particular bishops.

In a press conference on Monday ahead of the three-day meeting, two Chilean bishops said they came to Rome with 'pain and shame' given the seriousness of the abuse scandal in Chile.

The bishops, Fernando Ramos, auxiliary bishop of Santiago, and Juan Ignacio González of San Bernardo, said clerical sexual abuse is 'unacceptable' and 'intolerable,' and is something they are committed to eradicating, according to CNA.

Last month, Pope Francis summoned the bishops to Rome following an in-depth investigation into abuse cover-up by the Church in Chile, which resulted in a 2,300-page report on the investigation's conclusions.

The investigation focused on Bishop Juan Barros of Osorno, who was appointed to the diocese in 2015.

Pope Francis has performed a spectacular reversal over the claims. During a January visit to Chile, he appeared to dismiss claims that Barros covered up the abuse of three men by Fr Fernando Karadima, calling the victims' assertions 'calumny'. He then ordered the Vatican-led investigation and wrote an extraordinary letter on April 11 admitting to 'grave mistakes' in the handling of the affair.