The suspect, Hassan Mustafa Osama Nasr, says he was tortured in Egypt under questioning.

While the Americans are being tried in absentia, Pollari and other Italian spies are being forced to wage a legal battle that critics say could expose state secrets.

Pollari's lawyer requested that Berlusconi and outgoing Prime Minister Romano Prodi testify that documents covered by state secrets prove he had nothing to do with any kidnapping. Berlusconi has publicly defended Pollari in the past.

Judge Oscar Magi, who previously rejected a defence request that the trial be carried out behind closed doors, will decide on Pollari's latest request at the next hearing on May 14.

If Magi calls Berlusconi and Prodi as witnesses, they must testify.

The prosecution witnesses will also appear on May 14, including the head of the police investigation linking SISMI and the CIA to Nasr's disappearance. Nasr's wife will also testify.

Prosecutors say a CIA-led team grabbed Nasr, also known as Abu Omar, off a Milan street, bundled him into a van and drove him to a military base in northern Italy.

He was then flown to Egypt, where Nasr says he was tortured under interrogation with electric shocks, beatings, rape threats and genital abuse.

Nasr was freed from prison in February last year and lives in Egypt. He faces an arrest order in Italy on suspicion of terrorist activity. (Writing by Phil Stewart; editing by Philippa Fletcher)