Pope Francis returned from a brief respite today, a day after cancelling a visit to a hospital in Rome.

The Vatican said this was due to what it described as a "sudden indisposition".

Pope Francis met the Madagascan president today and delegates from the Orthodox Church and witnesses said the 77-year-old seemed tired but was smiling as he entertained his guests.

He had cancelled a trip to a hospital in Rome at the last minute, with a spokesman mentioning "the intense pace" of the pope's schedule by way of explanation.

"With so many undertakings, it's clear there's a need for a break every now and then," Vatican spokesman Federico Lombardi said.

The usually energetic pope gets up at five o'clock every morning, and often has a full day of religious and diplomatic engagements.

Local media reported that the pope was "very tired" and suffering from a headache made worse by a recent heat wave.