An Italian archbishop and staunch critic of Pope Francis has been excommunicated by the Vatican, its doctrinal office has said.

Carlo Maria Vigano was found guilty of schism - meaning he has split from the Catholic Church - after years of fierce disagreement with the pontiff.

The 83-year-old ultra-conservative has previously called on the Pope to resign, accusing him of heresy and criticising his stances on immigration, climate change and same-sex couples.

Archbishop Vigano was a senior figure in the Church, serving as papal envoy to Washington from 2011 to 2016.

In 2018 he went into hiding after alleging that the Pope had known about sexual abuse by an American cardinal and failed to act. The Vatican rejected the accusation.

Over time, the archbishop became associated with US conspiracy theorists, criticising Covid vaccines and alleging a "globalist" and "anti-Christian" project by the UN and other groups - both familiar conspiratorial themes.

On Friday the Vatican's doctrinal office said his refusal to submit to Pope Francis was clear from his public statements.

"The Most Reverend Carlo Maria Vigano was found guilty of the reserved delict [violation of the law] of schism," the statement said, adding that he had been excommunicated - or banished from the church.

Responding by a post on X, the archbishop linked to the decree that was emailed to him and said:

"What was attributed to me as guilt for my conviction is now put on record, confirming the Catholic Faith that I fully profess."

Archbishop Vigano was charged with schism and denying the pope's legitimacy last month. At the time, he write on X that he regarded the accusations against him as "an honour".

"I repudiate, reject, and condemn the scandals, errors, and heresies of Jorge Mario Bergoglio," he said, using the Argentine Pope's given name.

Pope Francis has put himself at odds with traditionalist Catholics by making overtures towards the LGBTQ+ community, championing migrant rights and condemning the excesses of capitalism.

Last year, he took action against another ultra-conservative critic, dismissing Bishop Joseph E Strickland of Texas when he refused to resign after an investigation.