Sex abuse scandals in the Roman Catholic Church are proof that that "the Devil is at work inside the Vatican", according to the Holy See's chief exorcist.

Father Gabriele Amorth, 85, who has been the Vatican's chief exorcist for 25 years and says he has dealt with 70,000 cases of demonic possession, said that the consequences of satanic infiltration included power struggles at the Vatican as well as "cardinals who do not believe in Jesus, and bishops who are linked to the Demon".

He added: "When one speaks of 'the smoke of Satan' [a phrase coined by Pope Paul VI in 1972] in the holy rooms, it is all true – including these latest stories of violence and paedophilia."

Father Amorth, who has just published Memoirs of an Exorcist, a series of interviews with the Vatican journalist Marco Tosatti, said that the attempt on the life of Pope John Paul II in 1981 had been the work of the Devil, as had an incident last Christmas when a mentally disturbed woman threw herself at Pope Benedict XVI at the start of Midnight Mass, pulling him to the ground.

Father Amorth told La Repubblica that the devil was "pure spirit, invisible. But he manifests himself with blasphemies and afflictions in the person he possesses. He can remain hidden, or speak in different languages, transform himself or appear to be agreeable. At times he makes fun of me."

He said it sometimes took six or seven of his assistants to to hold down a possessed person. Those possessed often yelled and screamed and spat out nails or pieces of glass, which he kept in a bag. "Anything can come out of their mouths – finger-length pieces of iron, but also rose petals."

He said that hoped every diocese would eventually have a resident exorcist. Under Church Canon Law any priest can perform exorcisms, but in practice they are carried out by a chosen few trained in the rites.