Italian Cardinal Angelo Becciu, who has been linked to a real estate scandal, resigned suddenly in one of the most mysterious episodes to hit the Holy See in years.

One of the most influential Vatican cardinals, Angelo Becciu of Italy, has resigned his position unexpectedly, the Holy See announced without explanation.

"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 one-line statement late on Thursday said.

After a career as a Vatican emissary, Becciu worked for the last six years as the Substitute for General Affairs, a role akin to the chief of staff, and one of Pope Francis' most trusted aides.