The Stasi spied on Joseph Ratzinger during the Cold War:

targeting him as one of the Vatican's fiercest opponents of communism, according to a report published on Sunday.

From April 1974 until the fall of the Berlin Wall in November 1989, the feared Ministry for State Security kept close tabs on the then theology professor Joseph Ratzinger, according to documents from the so-called Stasi archives printed in the weekly Bild am Sonntag.

"Ratzinger is seen at the Vatican as one of the staunchest opponents of communism," a Stasi spy noted in his file after the late John Paul II named Ratzinger prefect of the Congregation for the Doctrine of the Faith in 1981.

The report said the Stasi also attempted in vain to unearth damaging documents from Ratzinger's involvement in the Hitler Youth under the Third Reich.

An "unofficial collaborator" for the regime using the alias "Birke" (birch) reported on lectures Ratzinger gave at a seminary in the eastern city of Erfurt and recognised his importance to the Roman Catholic Church...

Stasi, "liberals", what's the difference you say.