A French nun who lived in London and said she saw the Eucharist turn to bloody flesh in the hands of a priest is to be put on the path to sainthood by Pope Francis, the Catholic Herald reports.

The Vatican has agreed to open the cause for the canonisation of Mother Marie Adele Garnier, the foundress of the Tyburn Nuns who died in Tyburn Convent, near Marble Arch, London, in 1924.

She has been given the title "Servant of God" after the Congregation for the Cause of Saints concluded that there were "no obstacles" to her candidacy.

The Catholic Herald reported that the development is expected to be formally announced by the Vatican later in the year.

The Vatican had been lobbied to open the Cause by Bishop Joseph de Metz-Noblat of Langres, a French diocese close to where Garnier grew up.

The prefect of the Vatican's Congregation for the Causes of Saints, Cardinal Angelo Amato wrote to the bishop during the summer instructing him to establish a tribunal within the diocese to examine Garnier's life and writings.

The conclusions of the local tribunal will eventually be sent to the Vatican and scrutinised by theologians and historians. Two miracles will be needed to be found in order for Garnier to be made a saint.

The assistant Mother General of the Tyburn Nuns, Mother Xavier McMonagle said the nuns had sought the opening of the cause for 20 years.

"It has been a long time, but that's not such a bad thing," she said. "It has given us time to research her writings."

Born near Dijon in 1838, Garnier worked as a governess and turned down a marriage proposal so she could establish her religious order in Montmartre, Paris, at the end of the 19th century.

She gathered a community of women dedicated to the "perpetual" adoration of the Holy Eucharist.

The Catholic Herald said that the burgeoning community was "persecuted by the Devil, with cases of obsession and diabolical possession and objects overturned, picked up and thrown around rooms."

In 1901, the nuns fled to London after the anti-clerical Law of Associations.

They came first to Notting Hill in west London and then in 1903, with the help of a cash gift, bought a house on the north side of Hyde Park. The house was just yards from the site of the Tyburn gallows, where 105 Catholics perished during the Reformation.

Garnier's order of contemplative Benedictine nuns, the Adorers of the Sacred Heart of Jesus of Montmartre, has in recent decades opened new convents in South America, Africa, France and New Zealand.

Pope St John Paul II invited the nuns to open a convent near the Vatican, asking them to pray for him and his successors.

In 2012 an Italian priest, Fr Gianmario Piga wrote a biography of Garnier, analysing her writings in depth.

The book, The Path of Mother Adele Garnier, revealed her to be a mystic who underwent experiences comparable to those recorded by such great spiritual writers as St Teresa of Avila and St John of the Cross.

In one letter to a priest friend, Abbé Charles Sauvé, she described how she saw the Sacrament turn to bloody flesh.

"At the moment in which the priest took a particle of the Holy Host and put it into the chalice I raised my eyes to adore and to contemplate the holy particle," she wrote.

"Oh, if you could know what I saw and how I am still moved and impressed by this vision. The fingers of the priest held not a white particle but a particle of striking red, the colour of blood and luminous at the same time ... The fingers of the priest were red on the right of the particle, as from a blood stain that seemed still wet."

The Vatican Press offered to publish the work and launch it in the Vatican's Marconi Hall on the Feast of the Sacred Heart of Jesus.

The main speech was given by Fr Federico Lombardi, then Pope Benedict XVI's spokesman.

The following year Pope Francis presented the nuns with an engraved gold chalice as a gift to mark the opening of their first French Convent at St Loup-sur-Aujon, near Dijon.

Cardinal Vincent Nichols last week celebrated Mass in Tyburn Convent to mark the golden jubilee of the Tyburn Association of Adoration, a lay movement which shares the perpetual adoration with the nuns.

The cardinal described Tyburn Convent as "a visible representation of the goal towards which the entire Church is journeying".

He added: "Mother Garnier wanted each one of her convents not only to be a place in which Jesus is continually adored in the Blessed Sacrament, but also to be a place in which lay people could share in this perpetual adoration. The association fulfils her deep desire."