Italy's highest court on Wednesday dealt a potentially fatal blow to the trial against 26 Americans accused of involvement in the alleged CIA kidnapping of an Egyptian terror suspect in Milan in 2003.

The Constitutional Court sided with the Italian government in saying that prosecutors used classified information to build the case and threw out some key evidence on which the indictments were based.

Though the judges did not formally throw out the indictments, lawyers said the ruling would at least set the case back.

State lawyer Massimo Giannuzzi said prosecutors would have to seek new indictments based on the remaining evidence or reopen the investigation altogether.

"We are quite satisfied," Giannuzzi said. "There will have to be a new preliminary hearing to decide if the remaining evidence is enough for new charges."

The American suspects — all but one identified by prosecutors as CIA agents — were accused along with seven Italian agents of kidnapping an Egyptian terror suspect from a Milan street on Feb. 17, 2003, in an "extraordinary rendition" operation coordinated by the CIA and Italy's SISMI military intelligence.

Prosecutors say Osama Moustafa Hassan Nasr, also known as Abu Omar, was then transferred to U.S. bases in Italy and Germany before being moved to Egypt, where he was imprisoned for four years. Nasr, who has been released, said he was tortured.

The Italian government denies any role in the operation, while the CIA has declined to comment on the case.

The trial in Milan was suspended pending the Constitutional Court's ruling, which had been delayed several times.

When the trial resumes, Judge Oscar Magi must turn over evidence deemed classified, notably files of thousands of dossiers on prominent public figures seized from the Rome apartment of a SISMI agent, Pio Pompa.

Also thrown out is testimony by Luciano Peroni, an intelligence officer allegedly at the scene of the kidnapping.

Wednesday's ruling was "a victory for the state attorney," said Alessia Sorgato, a lawyer defending several of the Americans, noting that Peroni's testimony had been "fundamental" to the prosecution's case.

However, most of the stricken evidence pertained to the Italian defendants, and Sorgato said it was still possible that the case against the Americans could continue.

She said the picture may become clearer once the court gives its reasoning on the decision, which may take weeks.

Giannuzzi noted the high court had not thrown out telephone intercepts of the suspects, as the government had requested, leaving them available as evidence in the case.

Prosecutors did not answer phone calls seeking comment.