The Vatican has encouraged followers to send birthday wishes by e-mail and is denying speculation the pope's apparent frailty might lead to his resignation, the ANSA news agency reported Monday.
"I find myself in the last stretch of the course of my life and I do not know what awaits me," the pope said in a statement. "I do know, however, that there is the light of God, and that He is risen."
"The Church is celebrating with joy as birthday greetings arrive from all over the world. The pope is leading us with great strength, kindness and faith, and therefore he is a gift from God," Federico Lombardi of the Holy See's Press Office told Vatican radio.
The birthday comes three days before the seventh anniversary of Benedict XVI's election to replace John Paul II.