A German magazine quotes one of the Vatican's top cardinals as saying that Pope John Paul is in very poor health and urged the faithful to pray for him.
The magazine Bunte says Cardinal Joseph Ratzinger described the pope as working too hard, and saying he will not slow down. Cardinal Ratzinger is a close aide to the 83-year-old pontiff.
On Sunday, the pope named 31 cardinals who will take part in choosing his successor.
The pope has become increasingly frail, last week canceling his weekly audience due to what officials called an intestinal problem. On a visit to Slovakia earlier this month he looked particularly weak.
Pope John Paul, who celebrates his 25th anniversary as the head of the Roman Catholic Church next month, suffers from Parkinson's Disease as well as hip and knee problems.