A Catholic Nigerian bishop who says he had a vision two years ago of Jesus handing him a roasary and saying "Boko Haram is gone", has declared that the terrorist organisation "will soon fizzle out".

In an interview with the Catholic Herald, Bishop Oliver Dashe Doeme of Maiduguri said: "Before, Boko Haram members were everywhere. But now they are not everywhere. They have been pushed to the forests."

The bishop went on: "Boko Haram will soon fizzle out, mostly because of the prayers of the people."

Bishop Doeme says that in 2014, he had a vision of Jesus handing him a sword which, as soon as the bishop received it, turned into a rosary. According to Doeme, Jesus then repeated the words: "Boko Haram is gone."

The bishop has since encouraged daily rosary processions throughout the diocese, in schools, homes and parishes.

Boko Haram - which has killed about 15,000 people and displaced more than 2 million in a seven year insurgency in Nigeria - has been on the retreat since 2014, though it still carries out attacks.

The Nigerian President Muhammadu Buhari, who took office last year, said in December that the group had been "technically defeated" because they were no longer able to mount conventional attacks, and that people who had been displaced by Boko Haram's attacks were now returning to their former neighbourhoods.

The diocese of Maiduguri has been at the centre of the attacks.

In 2014, more than 80,000 Catholics were displaced by Boko Haram's attacks, and more than 25 priests and 45 nuns had to flee.

Now, however, many of the displaced are returning, according to the Catholic Herald, and Bishop Doeme says caring for them is a bigger challenge than terrorist violence.

In an interview to be published in this week's Catholic Herald, Bishop Doeme says that he believes Jesus appeared to him appeared to him in 2014 "in order to console his people, that His Mother is there for us." He adds: "Boko Haram is evil, ISIS is evil. So as long as we go to a place with His Mother, especially by praying the rosary, which is the most pronounced form of Marian devotion, we will be victorious."

The interview comes as a new report shows that female members of Boko Haram are almost as likely as men to be deployed as fighters in north-east Nigeria.

According to the report by Finn Church Aid and based on interviews with 119 former Boko Haram members, four in 10 female respondents said they served as soldiers - compared with 45 percent of men - while both sexes carried out domestic tasks like cooking and cleaning.

"Recruiters are adapting to the tightening security environment," said Mahdi Abdile, director of research at Finn Church Aid and co-author of the study.

"The intelligence community is on the lookout for young men, so it is easier for women to navigate past security barriers and penetrate communities," he told the Thomson Reuters Foundation.