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 said on Thursday.

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 recognising 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.

The Vatican said Catholic faithful "must be attentive and cautious" in interpreting the alleged messages from Mary, which largely focus on themes of peace and piety, but also have warned of alleged coming world catastrophes.

Cardinal Victor Manuel Fernandez, head of the doctrine office, said the Vatican wished to act with an attitude of "great respect" toward a "spiritual phenomenon" that had attracted interest from Catholics across the world.

In 2021, Francis appointed a longtime Vatican diplomat, Archbishop Aldo Cavalli, as a special envoy to the Marian site. Fernandez said that Cavalli had described pilgrimages there as having an "atmosphere of God and of faith".

Thursday's statement directed Cavalli to continue in his role as envoy, and to take charge of assessing any possible future alleged messages from Mary given at the site.

The Vatican's Thursday statement was made under new rules approved by Francis in May for the evaluation of possible supernatural events. The rules, which replaced norms first drawn up in 1978, said bishops had to consult the Vatican when faced with reports of supernatural phenomena.