VATICAN CITY (AP) — Pope Benedict is resigning at the end of this month, making him the first pontiff to leave the papacy in nearly 600 years.

The 85-year-old Benedict announced his decision in Latin during a meeting of Vatican cardinals on this morning, saying that "my strengths due to an advanced age are no longer suited to an adequate exercise of the Petrine ministry."

The Pope told cardinals, "I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only by words and deeds but no less with prayer and suffering."

Benedict calls his choice "a decision of great importance for the life of the church."

The resignation of Pope Benedict sets the stage for a conclave to elect a new pope before the end of March, since the traditional mourning time that would follow the death of a pope doesn't have to be observed.

There are several papal contenders in the wings, but no obvious front-runner — the same situation when Benedict was elected pontiff in 2005 after the death of Pope John Paul II.