(ANSA) - Rome, July 16 - Nicole Minetti, one of three people standing trial for allegedly providing prostitutes for alleged sex parties at Silvio Berlusconi's home, has been told to resign from her post as Lombardy regional councillor for the former premier's People of Freedom (PdL) party. The call from PdL Secretary Angelino Alfano has been seen in the media as part of a bid by the party to purge itself of an element linked to corruption ahead of next year's general elections, when Berlusconi is expected to run for a fourth term as premier. Minetti, once Berlusconi's dental hygienist, responded to Alfano's call by saying "Why?" on Twitter. Political sources have said, however, that Berlusoni has persuaded her to step down.