Catholic faithful from all over the world cheered, filling a giant, 400,000-capacity, esplanade that faces the Sanctuary of Our Lady of Fatima, some of them crying -- with many more watching the canonisation from adjacent streets on giant screens.
"We declare the blissful Francisco Marto and Jacinta Marto saints," the Argentine pontiff said in front of the white basilica where the siblings are buried, two giant portraits of the little shepherds hanging in the background.
"We register them on the list of saints, declaring that they must be venerated as such by the Church."
The canonisation took place on the 100th anniversary of the day when Jacinta, then aged seven, her brother Francisco, nine, and their cousin Lucia, 10, first reportedly saw the Virgin Mary on the spot where the sanctuary was built.
She is said to have appeared six times between May and October 1917 to the three impoverished, barely-literate shepherds, and apparently shared three prophesies with the trio at a period marked by the ravages of World War I.
These reportedly included a warning of a second conflict.
Francisco died in 1919 and his sister Jacinta the following year in the Spanish Influenza epidemic that swept through Europe at the end of the war.
