ROME — Pope Leo criticized the global treatment of migrants and refugees and called on wealthier nations to help develop poorer countries during a press conference on Thursday after returning to Rome from a four-nation Africa tour. He did not reference any specific country when addressing the treatment of immigrants.

"They are human beings, and we have to treat human beings in a humanitarian way and not treat them worse than house pets or animals," Pope Leo said in the press conference. He also said wealthier countries should address conditions driving migration. "Countries have a right to control their borders, but richer nations should help develop the countries that migrants are leaving so they do not feel the need to leave," he said.

Leo, the first head of the Roman Catholic Church from the United States, has previously challenged U.S. President Donald Trump's hardline immigration policies and questioned whether they align with the Catholic Church's pro-life teachings. Those earlier remarks drew sharp criticism from conservative American Catholics.

Ahead of the Africa trip, Leo said he had no desire to engage the Trump administration in a public dispute. He also pledged to keep speaking on global conflicts and said the Vatican pursues dialogue and multilateral relationships among states to seek just solutions to problems.

Asked about reports that Iran killed thousands of anti-government protesters in January, Leo condemned the killings and said the Vatican maintains active diplomatic engagement even where it does not issue public statements.

Leo also defended his decision to visit Equatorial Guinea and Cameroon, both governed by long-term leaders, on the Africa tour. "The Vatican maintains diplomatic relationships with the governments of Equatorial Guinea and Cameroon," he said. "We don't always make great proclamations, but there's an awful lot of work that goes on behind the scenes to promote justice," Leo said.