The judges made the charges in a written explanation of their July conviction for abetting prostitution of former talent scout Lele Mora, TV anchorman Emilio Fede, and former Lombardy regional councillor Nicole Minetti, for organising sex parties for Berlusconi at his mansion outside Milan.
Several young women who testified for the defence confessed to receiving monthly payment from Berlusconi of at least 2,500 euros ($3,400), the judges said in the document.
Such behaviour was "not an anomaly, but an unlawful act", the judges wrote, adding that trial evidence had thus been "contaminated".
Judges accused Berlusconi of bribing witnesses at trial of three of his aides.
The judges said they had ordered Milan prosecutors to investigate the 77-year-old Berlusconi, the women who testified in his favour, and his lawyers Nicolo Ghedini and Piero Longo, for perverting the course of justice through graft, a crime that carries a four to 10 year jail term.
There was "serious proof", and witnesses used "identical" words and "language in their evidence statements, suggesting they had been coached, the judges said.
Berlusconi's legal team dismissed as fanciful the reasoning behind the July ruling, which was released months after the sentencing, as is customary in Italy.
"The explanations of the sentence, with regards to contaminating evidence, are completely disconnected from reality and from the facts," Longo and Ghedini said.
Fede and Mora were both handed seven-year prison sentences and banned for life from public office while Minetti was sentenced to five years in prison and banned from office for as many years.
All three are expected to appeal their convictions and sentences.
Last week, another court that convicted Berlusconi said in the explanation of its June ruling that he paid huge sums of money to have sex with an underage prostitute, who he knew was a minor at the time.
Berlusconi was said to have "systematically" tampered with evidence through bribes to witnesses in the case.
He was sentenced to seven years in jail and given a lifetime ban from public office in that trial, which he is appealing.