US President Donald Trump has attracted criticism from some Catholics after posting an AI-generated image of himself as the Pope.

The picture, which was shared by official White House social media accounts, comes as Catholics mourn the death of Pope Francis, who died on 21 April, and prepare to choose the next pontiff.

The New York State Catholic Conference accused Trump of mocking the faith. The post comes days after he joked to the media: "I'd like to be Pope."

Trump is not the first president to be accused of causing offence to the Catholic faith. Former US President Joe Biden, a Catholic, caused outrage a year ago when he made the sign of the cross at a pro-abortion access rally in Florida.

Vatican spokesman Matteo Bruni declined to answer questions about Trump's post during a briefing with journalists on Saturday. The Vatican is preparing to host a conclave to choose Francis's successor beginning on Wednesday.

The image posted by Trump on Friday night features him wearing a white cassock and pointed mitre, traditionally worn by a bishop. He wears a large cross around his neck, and has his finger held up, with a solemn facial expression.

The New York State Catholic Conference, which represents bishops in New York, took to X to criticise the picture.

"There is nothing clever or funny about this image, Mr President," the group wrote.

"We just buried our beloved Pope Francis, and the cardinals are about to enter a solemn conclave to elect a new successor of St Peter. Do not mock us."

Left-leaning Italian former Prime Minister Matteo Renzi also blasted Trump's post.

"This is an image that offends believers, insults institutions and shows that the leader of the right-wing world enjoys clowning around," Renzi wrote in Italian on X.

But the White House rejected any suggestion that the Republican president was making fun of the papacy.

"President Trump flew to Italy to pay his respects to Pope Francis and attend his funeral, and he has been a staunch champion for Catholics and religious liberty," said press secretary Karoline Leavitt.

The backlash continued on Sunday, as New York Archbishop Timothy Dolan, who has been friendly with Trump for years, told reporters that he disliked the image.

"It wasn't good," he said, after attending a Mass in Rome. "I hope he didn't have anything to do with that."

Switching to Italian, he called it a "brutta figura", a phrase meaning a bad or embarrassing impression.

Asked if the White House should take down the image and apologise, he said - again in Italian - "who knows" and declined to speak more about it.