Pope Francis has defrocked two Chilean bishops who have been caught up in the country's widening sexual abuse crisis, the Vatican said on Saturday.

The Vatican named the two men as Francisco José Cox Huneeus, archbishop emeritus of the city of La Serena, and Marco Antonio Órdenes Fernández, archbishop emeritus of Iquique.

A Vatican statement in Spanish said the pope's decision was definitive and not open to appeal. It referred to a part of Canon (Church) law related to the crime of sexual abuse of minors.

Defrocking, officially called "reduced to the lay state", means they have been expelled from the priesthood. It is the harshest punishment the Church can inflict on a member of the clergy and such action has rarely been taken against bishops.

Earlier this month, the religious order to which Cox belongs, the Schoenstatt Fathers, said the Vatican was investigating an accusation against him relating to the sexual abuse of a minor in Germany in 2004.

Cox, who is believed to have returned to Germany after a period in Chile, could not be reached for comment.

According to Chilean media, Órdenes, who resigned as bishop of Iquique in 2012 while under Vatican investigation, was accused of molesting a 17-year-old altar boy years ago.

He is believed to be living somewhere in Chile. It was not immediately possible to reach him for comment.

Last month Francis defrocked Father Fernando Karadima, an 88-year-old Chilean priest who sexually abused teenage boys over a period of many years and is at the centre of a wider abuse scandal that is still being investigated.