As record numbers of people flee conflict, persecution and poverty, governments, citizens and the Church have a moral obligation to safeguard migrants and show solidarity with them, the Pope has said.

"Contemporary migration movements represent the largest movement of individuals, if not of peoples, in history," the Pope told the International Forum on Migration and Peace at the Vatican on Tuesday.

"Unfortunately, in the majority of cases this movement is forced, caused by conflict, natural disasters, persecution, climate change, violence, extreme poverty and inhumane living conditions," he said.

The complex phenomenon poses a mounting challenge to host societies, which have a moral duty to welcome, protect, promote the "integral human development" of migrants, exiles and refugees and integrate them, he said.

"Defending their inalienable rights, ensuring their fundamental freedoms and respecting their dignity are duties from which no one can be exempted," he said.

The pontiff acknowledged the growing problem of unaccompanied minors, who even more than women are vulnerable to exploitation and abuse by human traffickers.

He urged special care for "children and young people who are forced to live far from their homeland and who are separated from their loved ones".

The Pope's wide-ranging address also urged "decent and appropriate shelter" for refugees and migrants, programmes to reunify families and give "the right to find in one's own homeland the conditions necessary for living a dignified life".