The Italian Cardinal-diplomat worked at the Vatican under five different Popes, being rewarded by Pope John Paul II in 1979 with the number two job at the Vatican, that of Secretary of State. He had been appointed roving ambassador in Eastern Europe by Pope John XXIII in 1961.

Cardinal Casaroli was the inventor of a new Vatican foreign policy towards the Communist states of Eastern Europe, many of which had openly persecuted Catholic clergy and lay people.

Cardinal Agostino Casaroli - Mastermind of Vatican's "Ostpolitik"

It was called the Ostpolitik, "eastern policy" in German, and enabled the Vatican to support Eastern European Catholics during the darkest days of the Cold War.

Cardinal Casaroli signed agreements between the Vatican and Communist Hungary in 1964 and with the former Yugoslavia in 1966. Later he conducted negotiations with the former Soviet Union, leading to the official visit by Mikhail Gorbachev to the Vatican in 1989.

When Cardinal Casaroli retired eight years ago, Pope John Paul thanked the Italian priest - his father was a tailor in the northern Italian town of Piacenza - for his work during such historic times. Cardinal Casaroli accompanied the Pope on many of his international journeys.

The BBC's Vatican Correspondent David Willey says:

"I remember meeting him once in the Vatican gardens with a book of Polish grammar under his arm.