Information from the allegedly illegal wiretap was published in Berlusconi's brother's conservative newspaper, Il Giornale, ANSA reported.
The recording was of a conversation in 2005 between Berlusconi's political opponent, Piero Fassino, head of the former center-left Democratic Left party, and Giovanni Consorte, the former chairman of Unipol, an association of insurers.
At that time, Unipol was about to take over one of Italy's largest banks, Banca Nazionale del Lavoro, and on the recording, Fassino can be heard saying, "We have a bank!"
Berlusconi said he had never heard the wiretap, "otherwise I would have remembered."
The Milan prosecutor requested Berlusconi's brother, Paolo, receive three years and three months in prison for the alleged offense.