(ANSA) - Rome, September 5 - Palermo prosecutors questioned ex-premier Silvio Berlusconi for three hours in Rome on Wednesday for investigations into alleged extortion by his former aide Marcello Dell'Utri. Berlusconi was accompanied by his lawyers Niccolo Ghedini and Luigi Longo. Prosecutors are investigating Dell'Utri over allegations he blackmailed Berlusconi to stay silent about the media-magnate's alleged relations to the mafia. Berlusconi, who is not under investigation in this case, has been called for questioning repeatedly but failed to attend a previous meetings on the grounds that he had official business which presented a "legitimate impediment". Berlusconi's daughter Marina was questioned by prosecutors in July. Marina Berlusconi is the president of the family holding company Fininvest and of its publishing group Mondadori. She is thought to have been asked about two loans made to Dell'Utri in 2003 to a total of over 1.1 million euros from an account held jointly with her father. Dell'Utri is set to have a retrial after receiving a seven-year jail sentence for allegedly helping the Mafia. Italy's supreme Court of Cassation in March ordered the retrial, saying Dell'Utri's legal rights had not been respected in the first appeal trial against the original conviction. But in its explanation of its decision to order a retrial, it said there was evidence that Dell'Utri had acted as an intermediary with the mafia for the ex-premier, handing on "substantial sums" of money for protection. Dell'Utri is a Senator in the ex-premier's People of Freedom party, which he is credited with helping to create in 1993 in its former form, Forza Italia.