Pope Francis on Sunday announced that he would elevate 21 churchmen to the high rank of cardinal, again putting his mark on the group that will one day choose his successor after his death or resignation.

The ceremony to install them, known as a consistory, will be held on Sept. 30, the 86-year-old Francis announced during his noon prayer to pilgrims and tourists in St. Peter's Square.

It will be the ninth consistory called by the pope since his election 10 years ago as the first pontiff from Latin America.

The new cardinals come from countries including the United States, Italy, Argentina, Switzerland, South Africa, Spain, Colombia, South Sudan, Hong Kong, Poland, Malaysia, Tanzania, and Portugal.

Eighteen of the 21 are under 80 and will be able to enter an eventual secret conclave to choose the next pope. They are known as cardinal electors.

After the September consistory, there will be 137 cardinal electors, about 73 percent of them chosen by Francis. This increases the possibility that the next pope will share his vision of a more progressive, inclusive Church.

Francis has also increased the possibility that the next pope will come from Asia or Africa, having consistently named cardinal electors from those continents and giving less importance than his predecessor to countries in Europe.

Whether the pope will name even more cardinals depends on how long he lives.

Francis spent nine days in hospital after surgery for an abdominal hernia last month. His recovery is going well and he is due to visit Portugal from Aug. 2 to 4 and Mongolia from Aug. 31 to Sept. 4.

The other three new cardinals, who are 80 or over and too old to vote in a conclave, were named to thank them for their long service to the Church.

All cardinals, regardless of their age, are allowed to take part in pre-conclave meetings, known as General Congregations, giving them a say in the type of person they think the younger cardinals should choose.

Cardinals rank second only to the pope in the Church hierarchy and serve as his closest advisers. Due to their historical power and influence, they are still called the princes of the Church, although Francis has told them not to live like royalty and to be close to the poor.

Three of the new cardinals were recently named as heads of major Vatican departments, including Argentine Archbishop Victor Manuel Fernandez, head of the Vatican's doctrinal department.

Another significant appointment was that of Bishop Stephen Chow Sau-Yan of Hong Kong. Chow is one of the major links to the Catholic Church in communist China, where the Vatican is trying to improve conditions for Catholics. The bishop visited Beijing in April.

Another is Archbishop Robert Francis Prevost, an American who was recently named head of the Vatican department that helps the pope choose new bishops, one of the most powerful posts in the Vatican.