BBC News, Rome
Pope Benedict XVI plans to relax restrictions on the celebration of the old Latin Mass, abandoned 40 years ago, Vatican officials say.
The Pope is reaching out to the conservatives in the Church
The so-called Tridentine Mass, in which the priest spoke in Latin and faced away from the congregation, was said around the world for 400 years.
But it was replaced, by the Second Vatican Council in the 1960s, with a Mass said in local languages.
The Vatican says the Pope wants to heal a rift with ultra-traditionalists.
A papal document is expected before Christmas outlining the Pope's reasons for allowing Catholics who pine for the old forms of their liturgy to hear the Mass once again in Latin.
At present it is very rare for bishops to allow the celebration of the Mass in what was the church's universal language for many centuries.
The background to this important policy change on the part of the Vatican is the challenge mounted by a small group of French and Swiss clergy.
They rebelled against the changes decided by the Council Fathers - among them the present pope - at the Second Vatican Council.
Their leader, Archbishop Marcel Lefebvre, now dead, was excommunicated by the late Pope John Paul II.
The followers of Archbishop Lefebvre are seeking reconciliation with the new pope, who has shown sympathy for their demands to be able to return to the old Latin rite if they wish.
Pope Benedict is much more in tune with the ideas of ultra-conservatives in the Catholic Church than was his predecessor.
His document is expected to reach out to them in order to end the schism which occurred when they broke away from Rome during the 1970s.