Pope Leo said on Sunday that doctors had detected a small growth on his lung during a recent health check and he would be undergoing surgery this week to remove it.

Leo, 71, told pilgrims in St. Peter's Square for his weekly Sunday prayer that the growth was "well-contained" and caught at an early stage.

"Recently, during some medical examinations, doctors found a localised nodule in my lung," the pontiff said. "It was detected at a very early stage and is well contained."

"The doctors believe it is advisable to intervene. So, following their advice, I have decided to undergo surgery to remove it," he said. "The operation is already scheduled for the next few days."

The Vatican press office said the pope's recovery from surgery was expected to take about a week.