Italy's highest criminal court has upheld the convictions of 23 US agents for abducting an Egyptian in Milan as part of the CIA extraordinary rendition programme.
The Wednesday ruling ends the final appeal in the first trial involving the CIA practice of abducting terror suspects and transferring them to third countries where torture is permitted.
The US citizens were convicted in absentia following a three-year trial and have never been in Italian custody.
They risk arrest if they travel to Europe and the verdict opens the way for the Italian government to seek their extradition.
Milan prosecutor Armando Spataro hailed the decision, saying it was tantamount to a finding that extraordinary rendition "is incompatible with democracy.
"We will see if the minister of justice intends to request extradition, since the final verdict poses this issue."
The CIA declined to comment.
The Americans and two Italians were convicted in November 2009 of involvement in kidnapping Osama Moustafa Hassan Nasr. The cleric was transferred to US military bases in Italy and Germany before being moved to Egypt, where he was tortured. He has since been released.
Those convicted include former Milan CIA station chief Robert Lady whose original seven-year sentence was raised to nine years on appeal.
The other 22 US citizens, all but one identified by prosecutors as CIA agents, also saw their sentences stiffened on appeal, from five to seven years.
The court also ordered new appeals trials for five Italian intelligence agents who had been acquitted because of national security considerations.