VATICAN CITY (AFP) - Pope Francis lambasted the Vatican's bureaucracy on Monday, saying some within the Church had a lust for power, were indifferent to others and suffered from "spiritual Alzheimer's".

The Argentine used a Christmas speech to cardinals, bishops and priests to list a catalogue of ailments plaguing some at the very top and urging a "cure".

He said the Vatican was riven with "existential schizophrenia", "social exhibitionism", "spiritual Alzheimer's" and a lust for power, all of which have led to an "orchestra that plays out of tune".

He warned against greed, egoism and people who think they are 'immortal'.

It is not the first time the 78-year-old has taken on the scandal-hit, intrigue-filled Curia, and called for them to renounce gossip and act responsibly.

Francis was elected in March last year on a mandate to overhaul the government and put an end to decades of infighting within the powerful but troubled body.

Since then the pontiff has establish a series of specialist bodies to tackle corruption and poor management in the Vatican, including the naming of eight cardinals from around the world to advise him on the Curia overhaul.