Pope Leo on Thursday decried the world's treatment of immigrants, saying that often migrants and refugees seeking to escape violence or poverty are considered "worse than house pets or animals," ‌in unusually strong remarks on the issue.

Leo, ​who has been a critic of President Trump's hardline immigration policies, called ⁠for humane treatment of immigrants while on his ​flight back to Rome after a four-nation Africa tour.

"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," the pope ​said in a ‌press conference.

Leo, the first U.S. Pope, did not mention ‌any specific country in his remarks on Thursday.

The Pope has previously questioned whether the Trump administration's hardline policies ⁠are in line ‌with the Catholic Church's ⁠strict pro-life teachings, in remarks that drew sharp criticism from ⁠conservative ⁠U.S. Catholics.

Leo said on Thursday that countries have a right ‌to control their borders. He urged richer nations to help develop the countries that migrants are leaving, so they ‌do ​not feel the need ‌to leave.

"What are richer countries doing to change the situation for poorer countries?" he ​asked. "And why can't we seek … to change the situations in (those) countries?"