The pontiff wore a white mask during the service at the Rome Basilica of Santa Maria in Aracoeli.

Previously he wore masks only in a car taking him to his weekly audiences in the Vatican.

He had come under some criticism, particularly on social media, for not wearing a mask at his general audiences and sometimes coming in relatively close contact with visitors.

Pope Francis, 83, attended the service with other Christian leaders in the basilica including the Patriarch Bartholomew, spiritual leader of Orthodox Christians.

Simultaneously in other locations in Rome, Jews were praying in the city's synagogue and Buddhist, Sikh, Hindu and Muslim leaders also prayed for peace.

The event took place as the number of people who have tested positive for the coronavirus has risen steadily in Italy in the past few weeks.

There has also been a relatively small spike in the Vatican, where four members of the Swiss Guards, the elite and colourfully dressed corps that protects the pope, have also tested positive for COVID-19.

The annual event was started by the late Pope John Paul and Rome's Catholic Community of Sant' Egido in 1986.

It was scaled down this year because of the coronavirus pandemic.

Pope Francis took off his mask while he read his address, as did other leaders when they spoke, but put it back on when he finished speaking.

Australian Associated Press