Pope Francis has approved a Catholic spiritual devotion centred in Medjugorje, a town in Bosnia that has been steeped in controversy over whether the Virgin Mary appears to local people.

The Vatican's doctrinal office said that Francis was not declaring that messages given by the alleged apparition of the Madonna were authentic. Rather, it said the pontiff was recognizing there were "positive fruits" for Catholics in the spiritual experience tied to the town.

Thursday's statement appeared to conclude decades of Vatican investigations into the alleged visitations, which were first reported by six children in 1981, in a scenario reminiscent of famous apparitions in the French town of Lourdes in the 19th century and more than 100 years ago in Fatima in Portugal.

The Bosnian village has become a major pilgrimage site, attracting hundreds of thousands each year and giving many people what they say is a renewed sense of spirituality.

Francis had previously expressed doubt about the alleged phenomenon. Referencing messages said to have been given by the Virgin Mary to local townspeople, he told reporters in 2017 that he did not think Mary was "the head of a telegraph office."

The Vatican said its new note "does not imply that the alleged supernatural events are declared authentic."

"Instead, it only highlights that the Holy Spirit is acting fruitfully for the good of the faithful 'in the midst' of this spiritual phenomenon of Medjugorje," said the text.