The incident, two days after Berlusconi announced he was planning to run in an election expected in February, came as a reminder of the sex scandals that plagued his last government and precipitated his demise.
Karima El Mahroug, also known by her stage name of "Ruby the Heartstealer", was due to testify yesterday but did not provide any valid justification for her absence, prosecutor Ilda Boccassini said in court.
Ms El Mahroug's lawyer, Paola Boccardi, said she did not know where her client was.
Ms Boccassini accused Berlusconi's lawyers of deliberately delaying the trial, in which the former premier is accused of paying for sex with Ms El Mahroug when she was under 18, to avoid a verdict in the middle of the election campaign.
Eighteen is the legal age limit for prostitution in Italy.
"This is a strategy to delay the proceedings while the election campaign gets under way," Ms Boccassini said in court.
Berlusconi's lawyer, Niccolo Ghedini, in turn said prosecutors were trying to hasten a verdict before the election, now expected in February rather than March or April after Prime Minister Mario Monti said he would resign early.
"It is the magistrates who have started the election campaign," Mr Ghedini told reporters.
The presiding judge in the case ordered police to search for Ms El Mahroug "throughout the national territory" and the trial was adjourned to December 17.
However, Ms Boccardi, said she did not know whether Ms El Mahroug would show up then. "I tried reaching her but her cellphone is off. She sent me a text saying she was abroad but I have no information about this trip and I don't know when she will be back," she said.
Ms El Mahroug's testimony in court has been requested by Berlusconi's defence team. Italian media said a few days before yesterday's hearing Ms El Mahroug had decided to travel to the US.
A verdict, which could deal a blow to Berlusconi's comeback hopes were he to be found guilty, is expected early next year.
The trial, in which dozens of aspiring showgirls have described the so-called "Bunga Bunga" parties at Berlusconi's residences, is the most sensational of his legal cases.
The 76-year-old billionaire, who has denied any wrongdoing, accusing left-wing magistrates of waging a politically motivated campaign against him, said last week he would seek re-election.
Meanwhile, European partners heaped praise on outgoing Italian Prime Minister Mario Monti. They called for the next government to stick to Mr Monti's reform agenda after his surprise decision to resign rattled financial markets pushing up Italy's borrowing costs and prompting a stock market sell-off.