Archbishop Loris Capovilla, 91, said there was no truth in the rumour that the Vatican was suppressing a vision of the end of the world.
The vision said to have been revealed 90 years ago by the Virgin Mary to three shepherd children on a hillside at Fatima in Portugal.
The three “Secrets of Fatima” were written down by one of the children, Lucia Dos Santos, who later became a nun.
Two of the secrets were revealed by the nun in 1941.
The first was a vision of hell, while the second apparently predicted the two world wars and the return of Russia from communism to Christianity.
The third secret, which was sent to Pope John XXIII in a sealed envelope in 1959, was only revealed by Pope John Paul II in 2000.
The Vatican said it referred to an assassination attempt on the pope in 1981 by a Turkish gunman, Mehmet Ali Agca.
However, many Catholics suspected that parts of the secret were not disclosed in order to avoid panic about the apocalypse.
The rumours swelled when the then Cardinal Joseph Ratzinger, now Pope Benedict, gave an interview in 1984 suggesting that the secret concerned “the dangers threatening the faith and life of Christianity, and therefore the world. And also the importance of our ultimate days”.
He added that the “things contained in this third secret correspond to what is announced in the Scripture”.
Antonio Socci, a journalist and author of The Fourth Secret of Fatima, said when he attempted to investigate the issue, he was denied access by the Vatican.
Nevertheless, Cardinal Tarcisio Bertone, the second-in-command at the Vatican, insisted earlier this year that conspiracy theories about an apocalyptic prediction were “pure fantasy”.
Today Mgr Capovilla, who witnessed Pope John XXIII opening the envelope of the third secret, said: “There are not two truths from Fatima and nor is there any fourth secret.
“The text which I read in 1959 is the same that was distributed by the Vatican. I have had enough of these conspiracy theories.
“It just isn’t true. I read it, I presented it to the Pope and we resealed the envelope.”
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