VATICAN CITY (Reuters) - Pope Francis will makes saints of two of the three Portuguese shepherd children believed to have seen a vision of the Madonna 100 years ago at Fatima, the Vatican said on Thursday.

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The pope, who is due to visit Fatima in May for the 100th anniversary of the reported apparitions, approved decrees recognizing miracles attributed to the intercession of Francisco Marto and his sister Jacinta Marto.

They died while they were still children several years after the visions. The third visionary, Lucia Dos Santos, became a nun and died in 2005 at the age of 97.

Francisco and Jacinta Marto were beatified - the last step before sainthood - by Pope John Paul in 2000.

The Catholic Church posthumously confers sainthood on people considered so holy during their lives that they are now believed to be with God and can intercede with him to perform miracles.

Miracles are usually the medically inexplicable healing of someone.

The Church believes that the Madonna gave the children three messages, the so-called three secrets of Fatima.

The first two were revealed soon and concerned a vision of hell, the prediction of the outbreak of World War Two, a warning that Russia would “spread her errors” in the world, and the need for general conversion to God and the need for prayer.

The “third secret” intrigued the world for more than three-quarters of a century, inspiring books and cults convinced that it predicted the end of the world.

In 2000, the Vatican said the third secret was a prediction of the 1981 assassination attempt on Pope John Paul on May 13, the same day of the first reported apparition in 1917.

The Vatican did not say when the sainthood ceremony of Jacinta and Francisco Marto would take place but Church sources said it was likely to be held during the pope’s visit in May.