Sister Lucia, a Roman Catholic nun, had been ill for the past three months and died Sunday at the Convent of Carmelitas in Coimbra, 120 miles north of Lisbon, TSF radio reported, citing family sources.
Prime Minister Pedro Santana Lopes called Lucia's death "very emotional news."
Lucia and two of her cousins, siblings Jacinta and Francisco, said in 1917 that the Virgin Mary had been appearing to them once a month and predicting events, such as world wars, the reemergence of Christianity in Russia, and one that Church officials say foretold the 1981 attempted assassination of Pope John Paul II. The appearances took place on the 13th day of each month in Fatima, a town about 70 miles north of Lisbon.
The first sighting was May 13, and the appearances took place for another five months, ending abruptly in October of that year.
Shortly after, both Jacinta and Francisco died of respiratory diseases. But Lucia became a nun and penned two memoirs while living in convents.
The Catholic Church later built a shrine in Fatima, which is visited each year by millions of people from around the world. More than 100,000 people from dozens of countries routinely attend the annual commemorations of the sightings.
The pope has visited three times since becoming pontiff in 1978, spending a few minutes with Lucia during a 1991 trip to the site. He has claimed the Virgin of Fatima saved his life after he was shot by a Turkish gunman in St. Peter's Square in 1981. The attack, on May 13, coincided with the feast day of Our Lady of Fatima, and John Paul credits the Virgin's intercession for his survival.
In 2000, he visited Fatima to beatify Jacinta and Francisco.