Pope John Paul II regularly whipped himself in 'remorse for his sins', a nun has revealed.
Pope John Paul, who died in 2005, is being considered for sainthood by the Catholic Church - the ultimate accolade and a tribute to his holiness.
As part of the Vatican's investigation, thousands of documents have been collected and examined by officials from the Congregation for the Causes of Saints.
Among them is the testimony of Polish nun Tobiana Sobodka, of the Sacred Heart of Jesus order, who worked for Pope John Paul in his private Vatican apartments and at his summer residence in Castel Gandolfo near Rome.
Sister Sobodka said: 'Several times he (Pope John Paul) would put himself through bodily penance.
'We would hear it - we were in the next room at Castel Gandolfo. You could hear the sound of the blows when he flagellated himself. He did it when he was still capable of moving on his own.'
The flagellation is also confirmed by another bishop who has given testimony, Emery Kabongo, who for several years was a secretary for Pope John Paul.
He said: 'He would punish himself and in particular just before he ordained bishops and priests. Before passing on the sacraments he wanted to prepare himself.
'I never actually saw it myself but several people told me about it.'