Polish communist priests were instructed to spy on Pope John Paul II by the secret police from 1946, a conference has heard.
Marek Lasota, director of the Krakow Institute of National Remembrance, said the Pope was identified as a problem for Communist party authorities in Poland a year after the end of WWII.
Speaking at a conference run by the University College Cork, Lasota said that 10% of Polish priests were acting on behalf of the regime, and that they were instructed to record anything and everything about the pope, including what underwear he wore and what food he liked.
"There was political pressure on the clergy. There were priests who infiltrated the Polish church. It was a complex situation," Lasota told the Irish Independent.
"[They were told to find out] what cosmetics does Karol Wojtyla liked. When does he shave? Who provides his meals? Who does his laundry? Does he play cards?"
When he was appointed a cardinal in 1967, John Paul II had been under surveillance by the secret police in Warsaw for over 20 years.
The Communist party was hoping to gather information that could be used to blackmail him but it was unable to find any dirt on him.
"Despite all the myths that he was an actor, he proved to be a very able organiser. His very important ability was that he was able to analyse a political situation within Poland or outside Poland," Lasota added.
Pope John Paul II would later become instrumental in bringing down the Communist party in central and eastern Europe by giving Polish people to confidence to demand change.
In 2004, he was nominated for a Nobel Peace Prize honouring his life's work in opposing Communist oppression.