Prosecutors are investigating whether Italian Premier Silvio Berlusconi paid for sex with an under-age girl from Morocco and then abused his power in trying to cover up the encounters.
Mr Berlusconi dismissed the case as "absurd" and said the prosecutors were just jealous they were not invited to his home for dinner too; the teenager has said she dined at the premier's Milan estate but did not have sex with him.
"At least my lawyers are happy," he quipped in an audio message to his supporters on Friday night. "They're sure that with me they'll never be out of work."
The investigation escalated a long history of accusations of sexual and financial impropriety aimed at the billionaire businessman, who has become Italy's longest-serving post-war leader despite corruption trials, international gaffes and political infighting.
The latest allegations come at a moment of particular vulnerability for the prime minister. Berlusconi has been politically weakened in recent months by a challenge from an ex-ally, while a law shielding him from two unrelated trials in Milan was significantly watered down yesterday by a ruling of Italy's Constitutional Court.
A citizen group has called for his resignation but his supporters immediately dismissed the allegations as a baseless, politically-driven attack.
According to a statement by Milan prosecutors, the probe is looking into whether the 74-year-old premier had sex with a 17-year-old nightclub dancer nicknamed Ruby, and then used the powers of his office inappropriately in trying to hide the encounter.
The prosecutors issued a summons for Berlusconi and his lawyers to appear for questioning, the statement said. They also ordered Milan police to search the offices of various people implicated in the case, including a showgirl-turned-politician who is close to the premier.
No date was given but the ANSA news agency said the questioning might take place next week, and that prosecutors might seek a fast-track trial.
Mr Berlusconi said the timing of the investigation was odd given the Constitutional Court ruling a day earlier, which he said was questionable but nevertheless confirmed the validity of the immunity law.