The 71-year-old pontiff said on Sunday that the nodule was discovered during a medical examination and had been detected at an early stage.

The Vatican Press Office said the pope would be admitted before midday on Tuesday, although it did not disclose the exact time of the operation.

Despite the upcoming procedure, Pope Leo continued with his normal duties on Monday, attending seven scheduled meetings during the morning.

He met bishops from Argentina, Nicaragua and the United States, as well as members of a charitable organisation based in Rome. During the meetings, he thanked the charity workers for their efforts and spoke in a strong, clear voice.

The Vatican expects the pope to spend about a week recovering after the operation.

A lung nodule is a small growth in the lung that does not automatically mean a person has cancer. The American Lung Association says most lung nodules are benign, with the likelihood of cancer depending on factors such as a person’s age, the size of the nodule and their smoking history.

Dr Federico Venuto, head of thoracic surgery at Policlinico Umberto I hospital in Rome, said removing such nodules can often be done using minimally invasive surgery.

The procedure may involve a thin tube fitted with a camera, allowing surgeons to examine the chest and remove the nodule through small incisions rather than making a large cut.

“The risk of complications after surgery is very low,” Venuto told Reuters.