Pope Francis sharply criticized U.S. President Donald Trump's immigration crackdown in an unusual open letter to America's Catholic bishops on Tuesday, saying criminalising migrants and taking measures built on force "will end badly".

In the letter, the pope said the criminalization of migrants and the mass deportations planned by the U.S. government are dangerous and called the country's current immigration policies a “major crisis.

Francis took the remarkable step of addressing the U.S. migrant crackdown in a letter to the bishops of the United States, who have criticized the expulsions as harming the most vulnerable. History's first Latin American pope has long made caring for migrants a priority of his pontificate,