Russian Orthodox Church leader Patriarch Kirill worked for Soviet intelligence in Switzerland in the 1970s. This is reported by the Sonntagszeitung and Le Matin Dimanche newspapers, AP writes.
The newspapers have read the Swiss police's previously classified documents about Kirill.
Kirill is often described as "Putin's Pope" and is one of the president's most devoted supporters, and also of the war in Ukraine.
In the 1970s, he was the official representative of the Russian Orthodox Church at the World Council of Churches. The newspapers write that the KGB's goal was to get the World Council to distance itself from the United States and its allies.
The patriarch's nephew Mikahail Gundayev, who today represents the Russian Orthodox Church at the World Council in Geneva, tells the newspapers that his uncle was not a spy but that he was kept under the "strict supervision" of the KGB.