VATICAN CITY (REUTERS) - Pope Francis said on Sunday (May 20) he would elevate 14 Roman Catholic prelates to the high rank of cardinal, the elite group of churchmen who are his closest advisers and can enter a conclave to choose his successor if they are under 80.

The pope made the surprise announcement during his weekly Sunday address. He said the ceremony to elevate the nominees, known as a consistory, would take place on June 29.

Appointing new cardinals is one of the most significant powers of a Pope, allowing him to steer the future of the 1.2 billion member Catholic Church.

After the June ceremony, Pope Francis will have nominated 74 cardinals since being elected Pope in 2013, according to statistics on the Vatican's website.

Only cardinals under the age of 80 can enter the closed-door conclave which chooses from its ranks a new pope and are known as "cardinal electors".

It was not immediately clear how many of the 14 qualify.

Two of those named by the Pope are Bishop Luis Ladaria Ferrer, head of the Vatican's doctrinal department, known as the Congregation for the Doctrine of the Faith, and Archbishop Angelo Becciu, deputy secretary of state.

Both currently work in the Vatican's central administration, known as the Curia.