Milan, December 20 - A Milan prosecutor on Thursday requested ex-premier Silvio Berlusconi be sent to prison for one-year for involvement in the publication of an illegally obtained wiretap in his brother Paolo's conservative newspaper Il Giornale. The prosecutor requested a jail term of three years and three months for Paolo Berlusconi. A verdict on the trial is expected to be given in January. The wiretap concerned a conversation in 2005 between one of Berlusconi's political opponents, Piero Fassino, the then head of the former centre-left Democratic Left (DS) party, and Giovanni Consorte, the former chairman of Unipol, an association of insurers historically linked to the DS, the heir to Italy's Communist Party. At the time Unipol came close to taking over one of Italy's leading banks, Banca Nazionale del Lavoro (BNL), and Fassino was recorded as saying "we have a bank!". Fassino, now mayor of Turin, was widely criticised for the comment, especially among the rank and file of the DS, which has since turned into a larger centre-left group, the Democratic Party. Fassino's lawyer said Thursday that the mayor would sue the Berlusconi brothers for a million euros for "enormous moral, political and existential" damage. Niccolo' Ghedini, Berlusconi's lawyer and an MP for his People of Freedom (PdL) party, said Thursday's request was part of a campaign by prosecutors to discredit the media magnate, who will stand for a fourth term as premier in elections in February. Ghedini said Milan magistrates were trying to have "a major influence on the result of the elections". Before being indicted, Berlusconi told a Milan court that he had never heard the wiretap, adding "otherwise I would have remembered". The Milan prosecutors's version of events is different. They say Paolo Berlusconi was allowed to hear the tape, before it was even logged in as evidence, by Roberto Raffaelli, the head of the firm Research Control System (RCS) which had been contracted by criminal investigators to make the wiretap. Several weeks later Raffaelli and a businessman friend, Fabrizio Favata, allegedly went to Silvio Berlusconi's private mansion in Arcore, outside Milan, and played it for the premier and, again, his brother before handing over a copy. A transcript of the Fassino-Consorte conversation was published several days later in Il Giornale. The investigators allege that Silvio Berlusconi was blackmailed by Favata over the handing-over of the wiretap but failed to report this for "almost three years". In October Berlusconi was sentenced to four years in jail in relation to tax fraud in the trading of film rights for TV broadcasts by his Mediaset media empire. His appeal against that sentence, which also banned him from holding public office for five years, is set to start in March. In Italy convictions for non-violent crimes do not usually become effective until the double appeals process has been exhausted. Due to a 2006 amnesty law, Berlusconi will not have to serve three of the four years of that jail sentence if the ruling is upheld. Berlusconi is also on trial for allegedly having sex with an underage alleged prostitute nicknamed Ruby during his third stint as premier and and using his position to allegedly try to hush it up. In the ongoing and several other previous trials, Berlusconi has always denied wrongdoing, claiming he is the victim of a minority group of allegedly left-wing prosecutors and judges who he says are persecuting him for political reasons. Berlusconi has been tried some 30 times but has only been convicted three times - verdicts that were either timed out or overturned on appeal - prior to the Mediaset fraud verdict.