Pope John Paul II had a pen pal in Polish writer

Cardinal Wojtyla (Pope John Paul II) and Anna-Teresa Tymieniecka (in blue) on a camping trip in 1978

London: Pope John Paul II had an intense relationship with a married Polish-born American philosopher for more than 30 years, according to previously unseen letters featuring in a BBC documentary that revealed a rarely seen side of the late pontiff.

Cardinal Wojtyla (Pope John Paul II) and Anna-Teresa Tymieniecka (in blue) on a camping trip in 1978. Pics/BBC

The former Vatican chief's letters to writer Anna-Teresa Tymieniecka, which feature in the documentary being shown by the BBC yesterday, had been kept away from public view in the National Library of Poland for years. The letters do not indicate that the Pope, who died in 2005 at the age of 84, broke his vow of celibacy, but the tone of some of his letters to her points to intense feelings between them, the broadcaster said.

Polish writer Anna-Teresa Tymieniecka

The letters show that the friendship began in 1973 when Tymieniecka contacted the future Pope, Cardinal Karol Wojtyla, then Archbishop of Krakow, about a book on philosophy that he had written. The then 50-year-old travelled from the US to Poland to discuss the work.

Shortly afterwards, the pair began to correspond. At first the cardinal's letters were formal, but as their friendship grew, they become more intimate. The two spent camping and skiing holidays together and went on country walks.

In 1976, Cardinal Wojtyla attended a Catholic conference in the US. Tymieniecka invited him to stay with her family at their home in New England. She appeared to have revealed intense feelings for him because his letters immediately afterwards suggest a man struggling to make sense of their friendship in Christian terms.

He goes on to describe her as a "gift from God". The BBC has not seen Tymieniecka's letters. They were not with the Pope's letters when they were shown to the BBC.