Nadia Macri, 28, told Sky TG24 Sunday that she believed many of the women - Brazilians and Russians mostly - were minors, but didn't know for sure since they didn't talk among themselves.
Macri is the latest woman to recount evenings spent at Berlusconi's villas - allegations that have fueled a political crisis that has brought the government to a no-confidence vote in two weeks.
Italian newspapers earlier this month published transcripts of Macri's testimony to prosecutors in which she said Berlusconi paid her ¬10,000 for sexual favors at the parties.
Berlusconi attorney Niccolo Ghedini said Sunday that Macri's comments were "devoid of any foundation" and had been disproved.
Macri limited her comments Sunday to how she was first introduced to Berlusconi - via a television executive - and how the premier allegedly contacted her by cell phone to invite her to a 2009 party at his villa in Sardinia and a 2010 party in Milan.
She said he introduced himself the first time by saying "I'm the dream of all Italians."
She declined to elaborate on her testimony to prosecutors about what went on during the parties, citing the ongoing investigation. She said, though, that she had spoken to the premier about apparent custody problems she was having involving her 6-year-old son.
In transcripts of her testimony published in Italian daily Corriere della Sera earlier this month, Macri said there was hashish available for the girls in some of the rooms of Berlusconi's Sardinia estate during the 2009 party.