ROME — Italy’s former military intelligence chief was sentenced to 10 years in prison on Tuesday for complicity in the C.I.A.’s abduction of an Egyptian Muslim cleric under a program begun after the Sept. 11 terrorist attacks.

The appeals court, in Milan, sentenced the former chief, Niccolò Pollari, to 10 years and his former deputy Marco Mancini to nine years for their role in the kidnapping of the cleric, Hassan Mustafa Osama Nasr, also known as Abu Omar, from the streets of Milan in 2003. Three Italian secret service officials were also sentenced to six years each.

Twenty-three Americans, including Robert Seldon Lady, a former C.I.A. base chief in Milan, were tried in absentia in the Abu Omar case in 2009 and convicted. All but one of them were C.I.A. agents. Three other Americans indicted in the case, including Jeffrey Castelli, the former C.I.A. station chief in Rome, were given diplomatic immunity and acquitted in 2009, but earlier this month, the Milan court vacated the acquittals and convicted them in absentia. Mr. Castelli was sentenced to seven years in prison and the other two to six years.

Mr. Nasr was kidnapped under the practice of “extraordinary rendition,” in which people suspected of being Islamic militants were abducted in one country and then transferred to another, often one where torture was common.