Pope Francis on Wednesday highlighted his background as a son of immigrants in his opening speech at the White House, immediately putting the plight of migrants at center stage during his US visit.

"As the son of an immigrant family, I am happy to be a guest in this country, which was largely built by such families," the pontiff said at the White House. "I would like all men and women of good will in this great nation to support the efforts of the international community to protect the vulnerable in our world."