Continuing the "Mercy Friday" visits he began during the Year of Mercy, Pope Francis chose a public housing complex in Ostia, a Rome suburb on the Mediterranean Sea.

The Vatican press office said Father Plinio Poncina, pastor of Stella Maris parish, put up signs May 17 announcing a priest would be visiting the neighbourhood to bless houses. The signs, which indicate a date and give a time frame, are a common site in Italy in the weeks before and after Easter.

"It was a great surprise today when, instead of the pastor, the one ringing the door bells was Pope Francis," the press office said. "With great simplicity, he interacted with the families, he blessed a dozen apartments" and left rosaries for the residents.

"Joking, he apologized for disturbing people, however he reassured them that he had respected the hour of silence for a nap after lunch in accordance with the sign posted at the entrance to the building," the press office said.

The Pope's Friday visits to hospitals and hospices, homes for children, rehab centres and other places of care were planned for the Year of Mercy as tangible ways for the Pope to practice the corporal and spiritual works of mercy.

Although the Year of Mercy ended in November, the Pope restarted making Mercy Friday visits in March when he visited a home and educational centre for the blind and visually impaired.