The appeal court cut the amount Fininvest was ordered to pay from nearly $1 billion [Reuters]

Italian Prime Minister Silvio Berlusconi's family investment company, Fininvest, has been ordered to pay $797 million to a rival media group over the corruption-marred acquisition of publisher Mondadori in 1991.

Milan's appeal court, while upholding a 2009 verdict against Fininvest, reduced the damages from nearly $1 billion.

The civil damage award stems from a case in which three Berlusconi associates were convicted of corrupting a judge to overturn a ruling in favour of industrialist Carlo De Benedetti in the struggle for control of Mondadori.

Berlusconi's daughter Marina Berlusconi, who heads Fininvest, said the verdict was unjust and part of a campaign against her father.

She complained that the award was worth twice Fininvest's share of Mondadori capital and said lawyers were already working on strategy to appeal to the nation's highest court.

Berlusconi came under fire this week when he introduced a measure into Italy's austerity budget that would have allowed Fininvest to delay payment until the final appeal. 

Berlusconi hastily withdrew the measure under opposition political pressure, but even allies claimed to have been unaware that the measure had been buried in the package.

"If you look at Fininvest's balance sheet, there is no economic threat for Fininvest itself," said LUISS law professor Roberto Pardolesi.

"I think it is unlikely that Berlusconi will suffer political damage because the worst part of the story, the corruption, has already been digested. This is a kind of conclusion on the story."

Still, the award comes at a time when the premier has been weakened by a series of electoral defeats in recent weeks. 

Not only did his candidates lose control of major Italian cities in local elections, including his native Milan, but voters reversed several key policies in referendums - including a law that partially shielded Berlusconi and other top officials from prosecution.

Berlusconi has faced dozens of court cases in Milan, most of them related to his business dealings. He has always denied wrongdoing, and in the final verdict has either been acquitted or seen the statute of limitations dropped.

Four cases are currently pending in Milan, including a trial in which Berlusconi is accused of paying for sex with an underage teen and then using his influence to cover it up. The trial continues later this month.

Berlusconi's lawyer, Niccolo Ghedini, who was not involved with the Mondadori case, expressed confidence that Italy's highest court would reverse the sentence. 

"The Milan court of appeals has handed down a verdict against all logic," Ghedini said.