Pope Francis on Sunday asked a group of elderly and sick members of Rome's seaside parish to pray for him because he, too, had grown old and was ailing.

"Pray for me, too, eh," Francis told the parishioners in a private meeting that was later broadcast by Catholic channel TV2000.

"I'm a little old and a little sick, but not too much," he said jokingly, drawing cheers and applause from the audience.

The 78-year-old pope later celebrated a Mass at the Ostia parish, a beachfront area of the capital.

The comment comes two months after Francis said in an interview with a Mexican broadcaster: "I have the feeling that my pontificate will be brief - four or five years, even two or three. Two have already passed."

While the pope is apparently in good health, there is always intense attention paid to a pontiff's condition, especially since Francis's predecessor stepped down in 2013 citing his advanced age and frailty.

Benedict, now known as Pope Emeritus, became the first head of the Roman Catholic Church in 600 years to resign instead of ruling until he died, and Francis has said Benedict's move should not be considered "an exception, but an institution".