Pope Francis has joked about the unprecedented cohabitation with his predecessor Benedict XVI in the Vatican, saying it is like living with a granddad.

Answering an array of questions during an 80-minute press conference on a flight back from Brazil, Francis spoke loving words of his predecessor, now Pope Emeritus.

"He is now living in the Vatican and people always ask me: 'Isn't it awkward? Doesn't he row against you?'" Francis said. "No for me it is like having a grandfather, a wise grandfather, living at home.

"If I've any trouble I can go and talk to him, as I did over the Vatileaks scandal."

The coexistence of two Popes was going far better than the last time it was tried in medieval times, Francis said.

"The last time there were two or three popes, they didn't talk among themselves and they fought over who was the true pope," Francis said. "I like Benedict; he is a man of god, humble, one who prays."

"He is cool" the current pontiff added, before landing at Rome's Ciampino Airport at the end of a week-long trip to Rio de Janeiro where he presided over the Roman Catholic World Youth Day (WYD) festival.

The Pope Tweeted:

Francis stepped off a special Alitalia flight carrying the same black luggage that attracted the world's attention when he left for Brazil.

"The keys to the atomic bomb weren't in it," Francis quipped. "I always carry my own luggage when travelling. It's normal.

"We have to get use to this being normal, this normalcy of life," added the man who has set a new humble course in the Vatican upon taking office earlier this year.

He said the bag merely contained a razor, his breviary prayer book, his agenda and a book on St. Terese of Lisieux, to whom he is particularly devoted.

Pope Francis
Pope Francis steps off a plane after returning from his trip to Brazil at Ciampino airport in Rome (Reuters)