Papal spokesman Joaquin Navarro-Valls told the ANSA and Apcom news agencies that the encyclical will carry the date of Dec. 25, 2005. It will be called "Deus, Caritas Est," and will have the Italian title of "Dio E' Amore," ("God is Love"), according to Apcom and other Italian news reports.
"The decision to make it public in January is due to the fact that the pope will release important documents over this period," Navarro-Valls was quoted as saying by Apcom.
Italian news reports had said the encyclical was to be published on Dec. 8.
The spokesman could not be reached for comment late Friday.
Earlier this week, he released an end-of-year message to cardinals and the Vatican curia.
Encyclicals are the most authoritative documents a pope can issue. Benedict's predecessor, the late Pope John Paul II, issued 14 encyclicals during his 26-year pontificate.