Pope Francis has missed a planned Mass with Rome clergy due to illness.

The Vatican said the 83-year-old pontiff had a "slight indisposition" and would proceed with the rest of his planned work on Thursday but Francis "preferred to stay near Santa Marta", the Vatican hotel where he lives.

There was no word from the Vatican about the nature of his illness, but the pope was seen coughing and blowing his nose during the Ash Wednesday Mass.

It comes amid an outbreak of the strain of coronavirus - also known as Covid-19 - in Italy that has infected more than 400 people, almost all of them in the north. Rome had three cases, but all three were cured.

Francis had been scheduled to go to the St John Lateran basilica to meet with Rome clergy and celebrate a penitential Mass at the start of Lent. Francis is bishop of Rome, but delegates the day-to-day running of the archdiocese to a vicar.

The Argentine pope has generally enjoyed good health. He lost part of one lung as a young man because of a respiratory illness, and suffers from sciatica, which makes walking difficult.

Francis has had a busy schedule lately, including his public general audience on Wednesday and the Ash Wednesday service later in the day in a Roman basilica.