Pope Francis has set up a commission to study the role of women deacons in early Christianity, the Vatican said on Tuesday, raising hopes among equality campaigners that women could one day have a far greater say in the Roman Catholic Church.

The Church bans women from all but a few decision-making roles and the pope and his predecessors have ruled out allowing them to become priests. But advocates said Francis's move might make it easier for a future pope to study whether to allow that.

Deacons, like priests, are ordained ministers, and, as in the priesthood, they must be men. They cannot celebrate Mass but they are allowed to preach and teach in the name of the Church and to baptize and conduct wake and funeral services.

The Church barred women from becoming deacons centuries ago.

Scholars debate the precise role of women deacons in the early Church. Some say they were ordained to minister only to other women, such as at immersion rites at baptism. Others believe they were on a par with male deacons.

A Vatican statement said the pope had chosen a group of six men and six women, led by a chairman, who is a bishop, "after intense prayer and mature reflection".

Most of the group are theologians and university professors. Of the six women, two are nuns and four are lay people.

Professor of theology and ministry at Boston College, Father James Bretzke, said the pope had "shown he is very much his own person. He is respectful of his colleagues and of his predecessors but he's not shackled by them".

"I think genuinely he's looking forward now, saying women have to have a greater role in the Church," said Bretzke, who, like the pope, is a member of the Jesuit order.

The Women's Ordination Conference, which advocates for a female priesthood in Catholicism, said it was encouraged by the fact that the group was gender-balanced and included lay people.

The group called the pope's decision "an important step for the Vatican in recognizing its own history of honoring women's leadership", because Biblical and historical evidence cited several women leaders working alongside men in the early Church.

"Only when women are equally included in all ordination rites - as deacons, priests, and bishops - and at all Church decision-making tables, can we begin to restore our Gospel values of equality and justice," the campaign group said.