Pope Francis has expressed openness to Catholic blessings for same-sex couples, provided they are not confused with marriage ceremonies for men and women.
The pope was responding to five cardinals who wanted clarification on same-sex couples and other issues, and a women's group that said only men should vote at the event.
According to a Vatican release, the cardinals had asked him for clarity on the issue, and he said any request for a blessing should be treated with 'pastoral charity'. He also suggested that the question of women's ordination to the priesthood, controversially banned by Pope John Paul II in 1994, could be reopen to further study.
"Pastoral prudence must adequately discern whether there are forms of blessing requested by one or more persons that do not transmit a false conception of marriage," the pope wrote in a letter dated September 25 and released by the Vatican on October 2.
"We cannot be judges who only deny, reject and exclude," he said. However, he added that the Church still considered same-sex relationships "objectively sinful" and would not recognise same-sex marriage.
"It is not just a matter of names, but the reality we call marriage has a unique essential constitution that requires an exclusive name that does not apply to other realities. It is undoubtedly much more than a mere 'ideal'," he said.
"For this reason, the Church avoids any kind of rite or sacrament that might contradict this conviction and suggest that something that is not marriage is recognised as marriage."
The pope offered a strong defence of the Church's long-standing teaching that marriage is between a man and a woman and must be open to children, saying it was important for the Church not to "lose the pastoral charity that must be part of all our decisions and attitudes".
On the question of women's ordination, he acknowledged John Paul's 1994 declaration in the apostolic letter Ordinatio Sacerdotalis that the Church has "no authority" to ordain women as priests, and John Paul's statement that the teaching must be "definitively held" by all Catholics.
But he also said there was "no clear and authoritative teaching ... on the precise nature of a 'definitive explanation. "
"It is not a dogmatic definition, and yet it must be accepted by everyone," the pope summarised.
"No one can publicly contradict it, and yet it can be an object of study, as in the case of the validity of ordinations in the Anglican Communion," he added.
The action was the latest clash between the pope and minority conservatives who have accused him of undermining a number of traditional precepts.
The request was one of several sent to the pope ahead of a week-long global meeting to discuss the future of the church, which begins at the Vatican on Wednesday.
Church leaders have been preparing for this week's closed-door meeting - known as a Synod of Bishops - for the past two years, asking Catholics around the world to share their vision for the Church's future.
The Synod of Bishops does not represent the College of Bishops, but is merely an advisory body to the pope, since bishops, as witnesses of the faith, cannot delegate their confession of the truth.
Topics include the role of women, greater acceptance of LGBT Catholics, social justice and the impact of climate change on the poor.
At the meeting, some 365 "members", including cardinals, bishops, lay people and, for the first time, women, will vote on proposals.
Discussions will run through this month and continue in October 2024. A papal document will follow, meaning that any changes to Church teaching would be a long way off.
Last month, a leading Catholic prelate in Kenya, who will be among those attending a Vatican synod of bishops, objected to a ruling by the country's Supreme Court allowing a gay rights group to be officially recognised as an NGO.
In an interview with the ACI news agency, Archbishop Martin Kivuva Musonde of the Archdiocese of Mombasa said the court's decision amounted to promoting an LGBTQ+ agenda in Kenya.
"It is very unfortunate. When you legalise something, it means you are promoting it," Kivuva said.
"If you register them (LGBTQ associations), it means you are giving life to the behaviours. If you join a football club, it means you are ready to play football," he said.
Archbishop Kivuva's comments came in the wake of a September 12 high court ruling that dismissed a challenge to an earlier decision to allow the National Gay and Lesbian Human Rights Commission (NGLHRC) to register as a non-governmental organisation.
Ten years ago, Kenya's NGO Coordination Board which is responsible for registering NGOs, rejected the group's application on the grounds that it 'promotes same-sex behaviour'.
In February however, Kenya's Supreme Court overturned that decision, in a latest ruling that confirms the group can register.
Kivuva said he couldn't understand why the court would grant LGBTQ+ people the right to form associations despite opposition from the country's highest authorities.
He also called on Kenyans to continue to defend themselves, echoing earlier statements made by the country's bishops regarding the ruling in February.
At the time, the bishops insisted that homosexuality "seeks to destroy life" and goes against the "natural order of being".