Pope Benedict XVI is bringing 22 new Catholic churchmen into the elite club of cardinals who will elect his successor.

Benedict, 84, is presiding over a ceremony in St Peter's Basilica in the Vatican to formally create the 22 cardinals, who include the archbishops of New York, Prague, Hong Kong and Toronto, as well as the heads of several Vatican offices.

But the ceremony has been clouded by embarrassing leaks of internal documents alleging financial mismanagement in Vatican affairs, and reports in the Italian media of political jockeying among church officials who, sensing an increasingly weak pontiff, are already preparing for a conclave.

The ceremony will bring to 125 the number of cardinals aged under 80 who are eligible to vote in a papal election. In all, the College of Cardinals now numbers 213.

Benedict was wheeled into St Peter's Basilica aboard the moving platform he has been using for several months to spare him the long walk down the centre aisle.

Benedict, who turns 85 in April, spoke in a strong voice as he told the cardinals they will be called upon to advise him on the problems facing the church.

In remarks at the start of the service, Benedict recalled that the red colour of the three-pointed hat, or biretta, and the scarlet cassock that cardinals wear symbolises the blood that cardinals must be willing to shed to remain faithful to the church.

"The new cardinals are entrusted with the service of love: love for God, love for his church, an absolute and unconditional love for his brothers and sisters even unto shedding their blood, if necessary," Benedict said.

At the end of his remarks, Benedict said: "And pray for me, that I may continually offer to the people of God the witness of sound doctrine and guide holy church with a firm and humble hand."