The pope's comments came in an interview by Vatican Insider, the online news supplement to the Italian newspaper La Stampa.
Asked about the dangers of sovereignty or nationalism, the pope said it represented an attitude of isolation and closure.
"A country must be sovereign, but not closed" he said.
The pontiff suggested national sovereignty should be defended but not at the detriment of relationships with other countries.
When he was asked about his views on immigration, Pope Francis said: "First and foremost never neglect the most important right of all: the right to life. Immigrants come above all to escape from war or hunger.
Concerning immigrants already in one's home country, certain "criteria must be followed," he said.
"First, to receive, which is also a Christian, Gospel duty. Doors should be opened, not closed. Second, to accompany. Third, to promote. Fourth, to integrate" the newcomers in the host communities, he said.
In the interview, Pope Francis said the upcoming Synod of Bishops on the Amazon is an "urgent" gathering, not of scientists and politicians, but for the Church, whose focus in discussions will be evangelisation.
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