MILAN, Italy - An Italian judge ruled Wednesday that Premier Silvio Berlusconi will be called to testify in the trial of 26 Americans and several Italians charged with kidnapping a terror suspect during a CIA operation.

Judge Oscar Magi approved the defense request as the case resumed. Magi also ruled that former Premier Romano Prodi and senior officials from both Berlusconi's and Prodi's past governments will be called to testify.

Berlusconi, who has just been elected to a new term, is considered a key witness because he was premier when Egyptian cleric Osama Moustafa Hassan Nasr disappeared in February 2003.

Italian prosecutors say Nasr, also known as Abu Omar, was abducted on a Milan street as part of the CIA's program of extraordinary rendition, in which terror suspects are moved from country to country without public legal proceedings.

The CIA has declined comment on the case.

It was not clear when Berlusconi and the others would testify.

Still pending is a Constitutional Court ruling. The Constitutional Court must rule on the government's request to throw out the indictments against the Americans. The government claims the case was improperly based on classified evidence.

A decision is expected when the Constitutional Court next meets, on July 8.

The trial in Milan will continue pending the decision.

Berlusconi's testimony had been requested by lawyers for Nicolo Pollari, a former intelligence chief who is one of the defendants in the case.

Pollari hopes the testimony might help prove that he was against the rendition, lawyers said. He could face from one to 10 years in jail if convicted.

Pollari has denied any involvement by Italian intelligence in the abduction.

Berlusconi, one of the United States' allies in its battle against terrorism, has expressed support for Pollari and has maintained his government was not informed about the operation and did not take part in it.

The trial is the first involving the CIA's extraordinary rendition program.

At the time of his disappearance, Nasr was also under investigation in Italy for suspicion of involvement in international terrorism.

Italian prosecutors say the cleric was transferred to U.S. bases in Italy and Germany before being moved to Egypt, where he was imprisoned for four years. Nasr, who was released last year, says he was tortured.

All but one American suspect in the case have been identified by prosecutors as CIA agents. They are being tried in absentia, and their Italian lawyers are all court-appointed, having had no direct contact with their clients.