A radical Egyptian cleric who was kidnapped in Milan as part of the CIA's secret rendition programme has been sentenced to six years in prison in his absence by an Italian court.

Osama Moustafa Hassan Nasr, also known as Abu Omar, was sentenced on charges of international terrorism. He disappeared from outside his flat in Milan in 2003 but now lives freely in Egypt.

His relatively well-documented abduction became one of the more notorious acts of the CIA's rendition programme after the 23 US agents and officials who organised and carried out the kidnapping were also sentenced to jail in absentia by an Italian court last year.

That trial strained relations between Washington and Rome and raised questions about abuse of diplomatic immunity. The Americans were given prison terms of between seven to nine years but are unlikely ever to be extradited to Italy to serve their sentences.

Italian prosecutors used mobile phone records to track Nasr's movements after the abduction and believed that CIA officers drove him to Aviano air base nearby before he was flown to Egypt.

The Mubarak regime detained him for a year during which, Nasr later alleged, he was beaten and subjected to electric shocks in a Cairo prison. He was freed in 2004 and told not to contact his family in Italy. He did and was subsequently rearrested and held for a further three years before finally being released in 2007 on condition that he remain in Alexandria.

Nasr denies he is or has been associated with terrorism in any way, said his lawyer. "It's a political trial, if you will, an ideological trial against someone who professes a political faith," Carmelo Scambia said.

Prosecutors reactivated the case against Nasr in May to complete the proceedings interrupted by the kidnapping. Maurizio Romanelli, the prosecutor leading the case, had sought a sentence of six years and eight months.

Nasr was found guilty of criminal association with the goal of terrorism and with aiding illegal emigration with the goal of terrorism, for allegedly helping organise false documents to help bring recruits to Islamic terror camps.

Italian prosecutors said Egypt did not respond to requests to question him or bring him to Italy for trial. Egypt's interior ministry told the Guardian there were no immediate plans to take further action following the Italian court ruling, and added that the ministry had not been monitoring the trial.