In comments to the Catholic news agency Ecclesia, Brás said that the confirmation came on Sunday, when he greeted the pontiff at the end of the service in the Vatican.
"I shall go, but to Fátima" was the pope's response, according to the bishop, to his comment that the Portuguese faithful "were expecting him".
Given the pontiff's words, Brás said, the visit to Fátima can be seen as certain unless something unforeseen comes up to prevent it.
According to Ecclesia, aside from the fact of his visiting Fátima, the programme remains open as to where he would arrive, the route he would takes to Cova da Iria - the part of Fátima where the shrine is located - and how many days he would be in the country.
The agency recalls that on 7 September last year, at a meeting with Portugal's bishops, the pope expressed a "deep wish" to visit Fátima.
On 17 March, Portugal's president, Marcelo Rebelo de Sousa, on a visit to the Vatican that was his first official trip abroad after taking office, formally invited Pope Francis to visit Portugal.
If he does come, Francis will be the fourth pope to visit Portugal, after Paul VI in 1967, John Paulo II in 1982, 1991 and 2000) and Benedict XVI in 2010.