Pope John Paul II has warned there are new difficulties in the path of unity between the Roman Catholic and Anglican churches. His comments came in his first meeting with the new archbishop of Canterbury, Rowan Williams.

The ailing and clearly fatigued pope held private talks with the new archbishop of Canterbury on Saturday, and warned him that new and serious difficulties have arisen in efforts to unite the Anglican and Roman Catholic churches.

During their 15-minute meeting, the pope, speaking haltingly in English, said some of these difficulties amount to essential matters of faith and morals.

Deep divisions over homosexuality arose between the two churches, following the recent ordination of an openly gay bishop by the Episcopal Church in the United States.

Speaking to reporters following his meeting with John Paul, Archbishop Rowan Williams said the Anglican Church is aware of the ecumenical implications.

"The need not to lose what has been gained in ecumenical agreement and discussion weighs very heavily," the archbishop said. "We are conscious of the ecumenical implications of what has been done. We shall need to consider those very carefully. We have, I think, in these days, listened hard to what has been said to us."

The archbishop is scheduled to hold an emergency meeting of the Anglican Church to discuss the matter in two weeks' time. He said he would relay to the Anglican summit the deep concern that the Vatican has over the issue of homosexuality

The Vatican opposes the ordination of homosexual priests. The Anglican Church has adopted a more liberal stance, but it also has become sharply divided over the ordination of the gay bishop in the United States.

Saturday's visit by the Archbishop of Canterbury was his first to the Vatican since his installation last February. While acknowledging the 83-year-old pope is undoubtedly struggling with ill health, he had words of praise for John Paul II.

"The most important impression that I would want to share from my meeting today is of that extraordinary and indomitable spirit and will, which lives within him," he said.

Pope John Paul's health has been in the spotlight in recent weeks, just as he prepares to mark another milestone in his papacy: his 25th anniversary as head of the Roman Catholic Church, on October 16.