The Pope's move in allowing groups of disaffected Anglicans to enter into full communion with the Holy See while retaining their Anglican heritage and traditions is seen by many in Britain as a stunning and potentially deadly blow to an already troubled and fragile Anglican Communion.

In Rome on Wednesday, by contrast, it was largely welcomed as a move toward helping to heal the 500-year-old post-Reformation schism. Some Vatican watchers said it could even in the long run affect the Catholic Church as much as the Anglican Communion.

At the Venerable English College in a cobbled Rome side street, the home of British Catholic seminarians since the 16th century, reactions were cautious. "It all depends what the Vatican means when it says Anglicans who join us can bring their traditions with them," said one guest at the opening of an exhibition celebrating the College's history. "It is all a bit sudden."

"A lot of things are unclear, including the consequences of this move," said Andrea Tornielli, Pope Benedict's biographer. "It is aimed after all not just at the traditionalists but at all Anglicans. I find it odd that the Catholic Bishops of England and Wales do not seem to have been consulted, and that the Pontifical Council for Christian Unity - which oversees the ecumenical dialogue for the Vatican - has been sidelined by the Congregation for the Doctrine of the Faith."

Mr Tornielli suggested that the departure of arch-conservative Anglicans might "make life easier for the Archbishop of Canterbury". Vittorio Messori, a Catholic writer who has co-authored books with Pope Benedict, said the Anglican Communion was already losing followers because of female and gay priests. "More Muslims go to the mosques in London than Anglicans go to church," he said. "The exit of half a million Anglicans to Rome will only confirm a trend which already exists."

But Avvenire, the newspaper of the Italian Bishops Conference, said the new set of canon laws, or "Apostolic Constitution", was a "healing gesture" and the "fruit of ecumenical dialogue". Cardinal William Levada, the head of the Congregation for the Doctrine of the Faith, also insisted the measures were a step in the Holy See's long efforts to heal the rift. Asked if the move posed a threat to ecumenism, he replied "Certainly not". He added: "The unity of the Church does nor require a uniformity that ignores cultural diversity, as the history of Christianity shows."

He declined to comment on whether the move would weaken the Anglican Church, noting only that "after the long years of the British Empire, and the work of Anglican missionaries, the Anglican Communion is a diverse and very varied worldwide communion."

"The Vatican's commitment to a rapprochement remains," said Luigi Accattoli, a veteran Vatican watcher. "And this move after all could have an effect on the Catholic Church itself if Anglican practices are introduced - less rigid confessional rules, for example, or new, mixed forms of worship. Those who enter the Catholic Church under the new rules will not just be Catholic converts, they will bring with them their own prayer books, vestments and rules of life - Anglican ones. This is something completely new."

Some Catholic canon lawyers wonder how Pope Benedict will square Anglican and Catholic teachings on issues such as priestly celibacy. Cardinal Levada on the other hand made clear that Catholic rules on celibacy would not change - and neither would the Vatican ban on female ordination. Asked what would happen if an Anglican parish led by a woman priest asked to convert to Rome under the new rules, he replied drily "I would be very surprised".