Pope Francis has recognised a second miracle attributed to Mother Teresa, clearing the way for the Roman Catholic nun to be declared a saint next year.

The miracle involved the healing of a Brazilian man with several brain tumours in 2008, the Vatican said.

Mother Teresa died in 1997 and was beatified - the first step towards sainthood - in 2003.

She won the Nobel Peace Prize for her work with the poor in the slums of the Indian city of Kolkata (Calcutta).

"The Holy Father has authorised the Congregation for the Causes of Saints to proclaim the decree concerning the miracle attributed to the intercession of blessed Mother Teresa," the Vatican said on Friday.

She is expected to be canonised in Rome in September.

Sister Christie, a spokeswoman for the Missionaries of Charity Mother Teresa founded in 1950, told the BBC that they were delighted by the news.

"Obviously all of us at the Missionaries of Charity are extremely happy. But we do not have any plans to celebrate this announcement as yet," she said.

Mother's charity: By Amitabha Bhattasali, BBC Bengali, in Kolkata

The Missionaries of Charity now has more than 4,500 nuns worldwide and is headquartered at the Mother House in central Kolkata.

In the city, the charity runs 19 homes - for women, orphans and the aged - where thousands of destitute people live. It also runs a school for street children, an Aids hospice and a leper colony.

Though the order's "service to the poorest of poor" has generated much appreciation worldwide, it's not without controversies.

The most recent controversy involves shutting down of its adoption centres in India.

The charity said it was forced to close the centres because India's new adoption laws, allowing single, divorced and separated couples to adopt, went against its religious views.

Profile of Mother Teresa

Beatification by the Catholic Church requires one miracle, while the process of becoming recognised as a saint requires proof of at least two miracles.

Mother Teresa was beatified in 2003 after Pope John Paul II accepted as authentic a miracle attributed to her.

He judged that the curing of an Indian woman suffering from an abdominal tumour was the result of the supernatural intervention of the late Mother Teresa - a claim challenged by Indian rationalists.

'Saint of the gutter'

There are few details about the recovery of the Brazilian man, whose life the Vatican says was saved in the second miracle.

His identity has not been disclosed to maintain the discretion needed for the investigation, the Catholic New Agency has said.

It says he was unexpectedly cured from brain tumours in 2008 after his priest prayed for Mother Teresa's intervention with God.

Mother Teresa was born Agnes Gonxha Bojaxhiu in Skopje, now Macedonia, then the Ottoman Empire, in 1910. Her family were ethnic Albanians, and devout Catholics.

She dedicated her life to caring for impoverished and sick people in Kolkata.

Known as the "saint of the gutter", she earned worldwide acclaim for her efforts.

Her critics, however, accused her of peddling a hardline Catholicism, mixing with dictators and accepting funds from them for her charity.

Her supporters justified the funding, saying it did not matter where the money came from as long as it was used to help the poor.