High-ranking Vatican official Cardinal Giovanni Angelo Becciu has unexpectedly resigned, the Holy See has announced.
He previously worked as the second-most senior official in the Vatican's Secretariat of State.
Cardinal Becciu became involved in a controversial deal to buy a luxury London building with church funds as an investment.
The deal has since been the subject of a financial investigation.
He denies any wrongdoing and has said he is shocked by the decision.
"The Holy Father accepted the resignation from the office of Prefect of the Congregation for the Causes of Saints and from the rights connected to the Cardinalate, presented by His Eminence Cardinal Giovanni Angelo Becciu," a statement from the Holy See said.
It gave no further details but such resignations are extremely rare.
Who is Cardinal Becchiu? Cardinal Angelo Becchiu, 72, was for years in Vatican terms a career diplomat.
From 2011 to 2018 he had the powerful role of Substitute for General Affairs in the Secretariat of State, when he met the Pope daily and was one of his most trusted aides.
It was Pope Francis who made him cardinal in 2018, when he took up a new role of running the department that looks after sainthoods and beatifications.
According to Italian reports, the Pope told him he had no choice but to resign on Thursday, shortly before the announcement was made public.
"It's a blow for me, my family, the people of my country.
I've accepted out of a spirit of obedience and love of the Church and the Pope," Italian media quoted the cardinal as saying on Friday morning.
Early evening in Vatican City: a powerful Cardinal and close ally of Pope Francis visits his boss for a reportedly tense meeting.
Giovanni Angelo Becciu had served as Deputy Secretary of State - a senior role with unfettered access to the Pope - and was now head of the department that chooses future saints.
In what's been dubbed "an earthquake at the Vatican", Pope Francis makes a rare move: "accepting the resignation" of Becciu (widely seen as firing) and stripping him of his rights as cardinal to choose the next Pope.
A terse statement is sent to the media reportedly as Becciu returns home.
The Cardinal, contacted by journalists, responds briefly: "I prefer silence.
" No reason has been given - but it seems Becciu fell on his sword after the London property controversy as well as other reported misdeeds such as allegedly propping up a failing Roman hospital which employed his niece.
The choreography of the dismissal, feeding the Vatican rumour mill, may seem cloak-and-dagger - but it is a reminder yet again that the scandal and corruption that beset governments across the world also reach the highest echelons of the Holy See.
Short presentational grey line What is known of the London property deal? It was during the cardinal's time as Substitute for General Affairs that he was linked to a luxury property deal in a wealthy area of London.
The $200m (£155m) purchase of the apartment block in Sloane Avenue was bought out of Church money through offshore funds and companies.
Five members of staff were suspended last year following a raid of the offices of the Secretariat last year.
Vatican police officers seized documents and computers Then, in June, Italian businessman Gianluigi Torzi was arrested by Vatican police on suspicion of extortion and embezzlement.
Earlier this year, Cardinal Becciu defended the purchase.
"An investment was made on a building.
It was good and opportune occasion, which many people envy us for today," he said in February.
He also denied that money collected for the poor, called Peter's Pence, had been used in the deal.
Why now? The cardinal's sudden departure may not just be linked to the London deal.
Italian reports suggest the Pope was unhappy with the use of the Peter's Pence funds for other investments, Last year, Italian weekly L'Espresso published a report from the Vatican's anti-corruption authority alleging more widespread speculative investments amounting to $725m.
Cardinal Becciu will keep his title despite his resignation from the congregation.
However, he will not be able to vote for the next Pope.
The last cardinal to give up his right to vote for a new Pope was Scottish Cardinal Keith O'Brien who resigned in 2013 amid a sex scandal.
He died five years later.