Vatican police have arrested a man over the leaking of secret papers and possessing confidential documents.
A statement from the Vatican said that the person was not a priest and was being questioned by Vatican magistrates, but gave no details.
The Vatican has been at the centre of a scandal involving the leak to Italian media of documents, some of them personal letters to Pope Benedict.
Some of the documents involved allegations of corruption, mismanagement and cronyism in the awarding of contracts for work in the Vatican.
They also indicated internal disagreement on the management of the Vatican bank.
The president of the Vatican Bank, Ettore Gotti Tedeschi, was ousted by its board yesterday.
The Pope is said to be shocked and saddened by the leaks.
He ordered several investigations, including one headed by Vatican police and another by a commission of cardinals.
Since the start of the year sensitive documents have been leaked to the Italian media.
They included letters by an archbishop who was transferred to Washington after he blew the whistle on what he saw as a web of corruption and cronyism.
Among the letters was a memo which portrayed a number of cardinals in a bad light and documents alleging internal conflicts about the Vatican Bank.
