(AP) -- Pope Francis has signed off on the miracle needed to make Mother Teresa a saint, giving the nun who cared for the poorest of the poor one of the Catholic Church's highest honors just two decades after her death.

The Vatican said Friday that Francis approved a decree attributing a miracle to Mother Teresa's intercession during an audience with the head of the Vatican's saint-making office on Thursday, his 79th birthday.

No date was set for the canonization, but Italian media have speculated that the ceremony will take place in the first week of September -- to coincide with the anniversary of her death, and during Francis' Holy Year of Mercy.

"This is fantastic news. We are very happy," said Sunita Kumar, a spokeswoman for the Missionaries of Charity in the eastern city of Kolkata (earlier called Calcutta), where Mother Teresa lived and worked.

Mother Teresa, a Nobel Peace Prize winner, died on Sept. 5, 1997, aged 87. At the time, her Missionaries of Charity order had nearly 4,000 nuns and ran roughly 600 orphanages, soup kitchens, homeless shelters and clinics around the world.

Francis, whose papacy has been dedicated to ministering to the poor just as Mother Teresa did, is a known fan. During his September 2014 visit to Albania, Francis confided to his interpreter that he was not only impressed by her fortitude, but in some ways feared it.

Francis recounted that he had met Mother Teresa, an ethnic Albanian, when they attended a 1994 bishop synod at the Vatican together. At the time, he was Archbishop Jorge Mario Bergoglio.

"Bergoglio had Mother Teresa behind him, nearby, and he heard her intervene often with great strength, without letting herself in any way be intimidated by this assembly of bishops," the Vatican spokesman, the Rev. Federico Lombardi, later recounted. "And from that he developed a great esteem for her, as a strong woman, a woman able to give courageous testimony."

But Bergoglio, who has long shown admiration for the women who raised him and taught him, added: "I would have been afraid to have had her as my superior, since she was so tough."

Mother Teresa was born Agnes Gonxha Bojaxhiu on Aug. 26, 1910, in Skopje, Macedonia.

She joined the Loreto order of nuns in 1928 and in 1946, while traveling by train from Calcutta to Darjeeling, was inspired to found the Missionaries of Charity order.

The order was established four years later and has since opened more than 130 houses worldwide to provide comfort and care for the needy, sick and "poorest of the poor."

Mother Teresa won the Nobel Peace Prize in 1979 for her work with Calcutta's destitute and ill -- work which continued even after she herself took sick.

"The poor give us much more than we give them," Mother Teresa said in 1977. "They're such strong people, living day to day with no food. And they never curse, never complain."

St. John Paul II, one of Mother Teresa's greatest champions, waived the normal five-year waiting period for her beatification process to begin and launched it a year after she died, convinced of her saintliness and apparently intent on at least beatifying her in his lifetime.

He bestowed that honor on her in 2003 in a Vatican ceremony.

The miracle needed for her canonization concerns the inexplicable cure in 2008 of a man in Brazil with multiple brain abscesses who, within a day of being in a coma, was cured, according to a report in Avvenire, the newspaper of the Italian bishops' conference. The Vatican ascertained that his wife's prayers for Mother Teresa's intercession were responsible, the report said.

Archbishop of Kolkata Thomas D'Souza said the news of the Vatican's decision was "the best Christmas gift one can get."

"We are grateful to God and we are extremely happy," he said.

While Mother Teresa is known and beloved by many around the world, she was not beloved by all. She was criticized for taking donations from Haitian dictator Jean-Claude Duvalier and disgraced American financier Charles Keating. Detractors opposed her stance against birth-control use in Calcutta's slums, which was nevertheless in keeping with church teaching opposing artificial birth control.

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