Jewish groups were angered in October 2008 when Pope Benedict spoke in favour of advancing the process to make the late Pope Pius XII a saint.

BBC: Pope in the Mid East: The issues

There were three rival claimants to the papal throne at that time - the Roman Pope Gregory XII, the Avignon Pope Benedict XIII, and the Antipope John XXIII.

BBC: How does a Pope resign from office?

Jews were also incensed at Benedict's constant promotion toward sainthood of Pope Pius XII, the World War II-era pope accused by some of having failed to sufficiently denounce the Holocaust.

NPR: Benedict Stumbled Trying To Right Troubled Church