Cardinal Vincent Nichols has said Pope Francis' ban on women ever becoming priests shows that he's a Catholic.

The Archbishop of Westminster and head of the Catholic Church in the UK dismissed outrage from women's campaign groups as he backed Francis' straight out refusal to ever ordain women.

"If Pope Francis has said we'll never have women priests I think it shows the Pope is a Catholic," Nichols told Christian Today.

The Pontiff told reporters aboard the papal plane on Tuesday that the ban on women entering the priesthood would remain forever.

"On the ordination of women in the Catholic Church, St Pope John Paul II had the last word on this and it stands," he said referring to an apostolic letter written by Pope John Paul II in 1994. The letter holds that ordaining women was not possible because Jesus chose only men as his apostles.

"This remains," he added.

When pressed on whether the ban would be in place "forever" Francis said: "If we read carefully the declaration by St John Paul II, it is going in that direction."

The declaration does not change the Argentine's stance and he has always said women could not be priests.

But pressure groups voiced their outrage at Francis' confirmation of John Paul's teaching. Women's Ordination Worldwide (WOW) said it showed he had a "blind spot as regards women".

A statement early on Wednesday morning read: "The oppression and poverty of women and girls around the world is reinforced when women and men are not seen as equally imaging God and this inequality in leadership, governance and ministry is reflected in our Church.

"It is long past due for the Church to rid itself of the sin of sexism and to welcome women as equal partners in all realms of ministry and leadership."

Catholic Women's Ordination added it was a "dangerous, untheological blind spot".

"The damage of this blind spot carries with it a tremendous responsibility on being a primary cause of the terrible violence and poverty that many women suffer on a daily basis; they are seen as second class and inferior to men," a statement read.

"Erroneous teachings in any church are highly dangerous as they tend to influence young, unformed minds, and are hard to shake off in adult life. This leads to a twisted formation of conscience and reducing people to a lesser understanding of their own personal dignity and a fear of an overarching demanding God rather than the true nature of the Goodness of God."