Juan Fernandez Krohn lunged at John Paul with a bayonet in 1982 during a ceremony in the shrine of Fatima in Portugal. (Inacio Ludgero-Visao/Reuters) The late Pope John Paul II was wounded in a 1982 knife attack a year after an assassination attempt, but kept the injury secret, a top aide to the pontiff has revealed in a new documentary film.

The attack occurred on May 12, 1982, when Juan Fernandez Krohn lunged at John Paul with a bayonet during a ceremony in the shrine of Fatima in Portugal.

John Paul went to the shrine to give thanks for surviving a gunshot wound from Turkish gunman Mehmet Ali Agca in St. Peter's Square on May 13, 1981.

The Pope's bodyguards immediately tackled and arrested Krohn, an ultra-conservative priest from Spain.

In the film Testimony, which was to be aired Thursday night in the Vatican, Cardinal Stanislaw Dziwisz reveals that the pope was cut in the attack, but continued on his trip without disclosing the injury.

"I can now reveal that the Holy Father was wounded. When we got back to the room [in the Fatima sanctuary complex] there was blood," Dziwisz says in the documentary.

The film is a combination of documentary footage and recreations of scenes from life of the Pope, who was born Karol Wojtyla. It is based on the memoirs of Dziwisz, who served at the Pope's side for almost 40 years and is now the archbishop of Krakow.

Krohn was expelled from Portugal in 1985 after serving half of a six-year jail sentence. He was later sentenced to four months in prison in Belgium for resisting arrest after breaching security and approaching Spain's King Juan Carlos and Queen Sofia during a royal visit to the country in May 2000.

Krohn was acquitted of a separate charge of setting fire to the Brussels headquarters of Basque separatist group Herri Batasuna in 1996.

John Paul II died in April 2005 at age 85.

With files from Reuters