Pope Francis has added his voice to those criticizing the Trump administration’s “zero tolerance” policy that has resulted in the separation of families at the Mexican border.

In a wide-ranging interview with Reuters at his Vatican residence published on Wednesday,World Refugee Day, Francis said he supported thestatements made by US Catholic bishops who called the separation of children from their parents “immoral” and “contrary to our Catholic values.”

“I am on the side of the Bishops’ Conference,” Francis told Reuters, referring to those statements. “It’s not easy, but populism is not the solution,” he added.

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CNN reported in Maythat the Trump administration had decided to refer anyone found crossing into the US illegally for federal prosecution, meaning that adults coming across the border with children are separated from them as the parents await their criminal proceedings.

Asharrowing imagesandaudio of children emerged from the border this week, Trump has come under increasing pressure to drop his “zero tolerance” policy. But Trump has defended his administration’s actions and falsely blamed the Democrats for the continuing separations.

The Pope added that it was not solely “a Trump issue.”

“During the Obama administration, I celebrated mass at Ciudad Juarez on the border,” he said, referring to his visit to the Mexican border city in 2016. “The problem already existed then. It’s not just a Trump issue but also one of the previous governments.”

In an interview with Reuters, Pope Francis criticized the Trump administration on a number of issues.

‘You cannot reject people who arrive’

In the rare interview, Francis, who has previously come under fire from more conservative cardinals for his teachings, defended his more liberal, outspoken approach to moral and social issues.

He insisted that the future of the Catholic Church was “on the street” and said he wanted to appoint more women to lead Vatican departments because they were better at resolving conflicts.

MYTILENE, GREECE - MAY 20: A refugee child plays alone at the Moria refugee camp on May 20, 2018 in Mytilene, Greece. Despite being built to hold only 2,500 people, the camp on the Greek island of Lesbos is home to over 6,000 asylum seekers who crossed the Aegean Sea from Turkey's nearby shore by boat, usually at night to avoid interception. Although the numbers of arrivals are lower than at the beginning of the crisis in 2015, when Syrians and Iraqis fled ISIS-controlled strongholds, boatloads of refugees from those countries and other troubled areas continue to land there, and critics say the local governments have yet to manage the situation, leading the squalid conditions at Moria to be seen as symbolic of poorly-managed policy. The camp, on the site of a former military base, is comprised of shipping containers, tents, and improvised shelters of wooden pallets and tarps, whose residents stranded there complain of poor food, power failures, disease, lack of medical care, and poisonous snakes as they wait to obtain transfer to the mainland and less temporary legal status. (Photo by Adam Berry/Getty Images)

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He also directly criticized Trump’s decisions to pull out of a climate change accord and to implement new restrictions on American travel and trade with Cuba last year.

But it was the subject of immigration that dominated the discussion, with the pontiff also taking aim at the response of some European governments to migrants and refugees arriving on the continent.

Seeming to referenceItaly’s refusal to allow a rescue ship with 630 migrants to dock in an Italian portlast week, he insisted that people arriving on Europe’s shores must not be turned away.

“I believe that you cannot reject people who arrive. You have to receive them, help them, look after them, accompany them and then see where to put them, but throughout all of Europe,” Francis said.

“Some governments are working on it, and people have to be settled in the best possible way, but creating psychosis is not the cure,” he added. “Populism does not resolve things. What resolves things is acceptance, study, prudence.”

Theresa May: ‘Deeply disturbing’

British Prime Minister Theresa May joined the condemnation of the Trump administration’s “zero tolerance” policy on Wednesday, describing the detention of children in cages as “deeply disturbing.”

Asked in parliament whether she would discuss immigration with Trump when he visits the UK in July, May said they would speak about “a range of issues” and that “when we disagree with them, we say so.”

“The pictures of children being held in what appear to be cages are deeply disturbing,” she said. “This is wrong, this is not something that we agree with, and this is not the United Kingdom’s approach.”

On Tuesday, Irish Taoiseach Leo Varadkar said he planned to convey his government’s “grave concern” about the controversial practice to the acting US ambassador.

CNN’s Delia Gallagher and Lindsay Isaac contributed to this report.