The organisers of the World Meeting of Families (WMOF) have rejected a call to cancel a speaking invitation to a Catholic priest who, objectors say, wrongly promotes the view that same-sex marriage is acceptable to the church.

The speaker, Fr James Martin, has said he hopes that Catholics who are LGBT will see the Vatican-approved invitation as "an unmistakable sign of welcome from the church".

The demand for the withdrawal of the invitation is made in an online petition organised by the Irish branch of the Tradition, Family and Property (TFP) organisation which has attracted over 10,250 signatures, many of them from supporters in the United States.

In a letter to Archbishop of Dublin Diarmuid Martin, TFP says the American Jesuit - who belongs to the same order as Pope Francis - should not be given a platform at the event in the RDS in Dublin because he "is well known for his dissent from church teaching on sexual morality" and "has articulated views which condone homosexual behaviour in contradiction of the Magisterium (teaching authority)."

Speaking to RTÉ's News at One, the TFP's Rory O'Hanlon said Fr Martin opposed what the church had taught down through the centuries on various aspects of sexuality, especially the homosexual issue.

Mr O'Hanlon agreed with Fr Martin's statement that all humans who have reached the age of reason are sinners and the church has to reach out to everybody.

But he added: "That's not exactly what he's saying in a lot of what he promotes. He's promoting the idea that, for example, same sex marriage is acceptable in the eyes of the Catholic Church which it never has been."

Mr O'Hanlon said the issue was important because "there's a lot of confusion in the church about its teaching on sexuality" since, and probably even before the publication 50 years ago of the Papal encyclical, Humanae Vitae, which had reiterated the Vatican's ban on artificial contraception.

"There was so much protest and objection to Humanae Vitae and ever since then.

"There's been a lot of confusion in the church about ... sexuality," he added.

But in a statement the WMOF organisers said that with just over a week to go to its pastoral congress in the RDS, "there will be no change to the line-up of speakers who have been invited to be part of the event.

"We are looking forward to welcoming all 292 speakers from around Ireland and from across the world to our gathering of families in Dublin," the statement concludes.

Fr Martin has said that the LGBT community "need to know that God loves them and their church accepts them."

Writing in America magazine, which he edits, he expressed his happiness at being invited to address the Dublin meeting.

"I'm tremendously grateful for this invitation, not so much for what it says about my own ministry or writing but what it says to LGBT Catholics, a group of people who have for so long felt excluded," he said.

"I hope they see this invitation, which had to be approved by the Vatican, as an unmistakable sign of welcome from the church."

'Pope Francis gets it' - dropped

Earlier this year references to LGBT people were dropped from promotional material produced by the WMOF.

A photograph of two women embracing and a video clip recorded by Irish-American Bishop David O'Connell were removed.

Co Cork-born Dr O'Connell who is an assistant bishop in the Archdiocese of Los Angeles said in the original version of the video that "Pope Francis gets it."

He goes on to explain that the pontiff recognises the different configurations of families today, including single parents or a gay couple raising children.

"He gets it that our society has changed so much in the last couple of generations," he told the makers of  'Amoris: Let's talk Family! Let's be Family!'.

"We have all sorts of configurations of families now, whether it's just the traditional family of mum and dad together, or it's now mum on her own or dad on his own, or a gay couple raising children, or people in second marriages.

"No matter what the configuration of the family is, the call is still to adults to think about how to provide the best, most loving, faithful environment for children possible," the bishop said.

Last week, Archbishop Martin, the host of the WMOF, said he did not censor Bishop O'Connell's statement.

Asked at a news conference who was responsible, he said: "I must say, if it happened in the World Meeting of Families I take responsibility as the person in charge if mistakes were made I take responsibility for those. But I take that responsibility by ensuring that the main thrust of the (World) Meeting is what it is (to welcome everybody)."

However, the Vatican's steward for the WMOF, Dublin-born Cardinal Kevin Farrell had already told RTÉ News that he did not drop the LGBT references either.

The invitation to Fr Martin is seen as an olive branch to Catholics who are LGBT who have protested vigorously at the censorship of the WMOF's original positive references to their place in the church.