The 86-year-old pontiff is recovering from the flu and inflammation of respiratory tract.

Francis, 86, was scheduled to leave on Friday to address the Conference of the Parties (COP28) in Dubai on Saturday. He would have become the first pontiff to address a UN climate conference.

He also was set to inaugurate a faith pavilion on Sunday on the sidelines of the event.

On Tuesday, Vatican spokesman Matteo Bruni said Francis’s health was improving after the flu and inflammation of his respiratory tract had forced him to cancel his audiences on Saturday, but the doctors advised him not to travel to Dubai.

The pope agreed not to travel “with great regret”, according to the Vatican statement, which added that it would look into ways that the leader of the world’s Roman Catholics could contribute to the climate discussions remotely.

Francis, who had part of one lung removed as a young man, came down with the flu last week and had a CT scan. The Vatican subsequently said the test had ruled out pneumonia.

On Sunday, he skipped his traditional appearance at his studio window overlooking St Peter’s Square to avoid the cold. Instead, he gave the traditional noon blessing in a televised appearance from the chapel in the Vatican hotel where he lives and asked a priest to read his written daily reflections out loud.

The pope had to postpone a trip to the Democratic Republic of the Congo and South Sudan in 2022 because of knee inflammation. He was able to make that journey early this year.

When asked about his health in a recent interview, Francis responded in what has become his standard line: “Still alive, you know.”