Pope Francis has fired the Texan bishop Joseph Strickland, a fierce critic who has questioned the Pope's leadership of the Catholic church.

The Vatican said the bishop would be "relieved" of his duties as a result of investigations at his Diocese of Tyler.

Bishop Strickland is a leading voice in a branch of US Catholicism that is opposed to the Pope's reforms.

His removal comes after Francis spoke of the "backwardness" of some US Catholic church leaders.

Bishop Strickland has launched a series of attacks on the Pope's attempts to update the Church's position on social matters and inclusion, including on abortion, transgender rights and same-sex marriage.

In July, he warned that many "basic truths" of Catholic teaching were being challenged, including what he called attempts to "undermine" marriage "as instituted by God" being only between a man and a woman.

He criticised as "disordered" the attempts of those who "reject their undeniable biological God-given identity".

His letter suggested that attempts to change "that which cannot be changed" would lead to an irrevocable schism in the Church. Those seeking change, he warned, "are the true schismatics".

Bishop Strickland was under investigation by the Vatican and had previously declined the opportunity to resign, and in an open letter in September challenged the Pope to fire him.

"I cannot resign as Bishop of Tyler because that would be me abandoning the flock," he said.

The right-wing "Coalition for Canceled Priests" held a conference earlier this year to support him during the investigation.

The Vatican said that the decision to fire him "came after an apostolic visitation ordered by the Pope last June in the Diocese of Tyler". According to Catholic media, the investigation also looked at the handling of financial affairs at the diocese.

Bishop Strickland, 65, was appointed bishop in 2012, while Benedict XVI was pope.

It all follows significant attempts made by the Pope to make the Church more progressive during his papacy.

On Thursday, the Vatican announced that transgender people can be baptised in the Catholic Church, as long as doing so does not cause scandal or "confusion".

In October, he suggested that the Church would be open to bless same-sex couples, as he told a group of cardinals "we cannot be judges who only deny, reject and exclude".

Speaking at a meeting at the World Youth Day celebrations in Lisbon the Pope said the backwardness of some people was "useless".

"Doing this you lose the true tradition and you turn to ideologies to have support. In other words, ideologies replace faith," he added.

Climate change has also been a key pillar of his papacy - from a landmark paper on the environment in 2015 to recent warnings that the world may be "nearing breaking point" due to climate change.

He has also strongly condemned climate deniers and will be at the United Nations' Climate Summit (COP28) later this month - the first time a pope has attended the event since they began in 1995.

The Vatican said that the Diocese of Tyler would be temporarily administered by Bishop Joe Vasquez of Austin. (BBC)

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