A U.S. federal appeals court has upheld a refusal to hear the case of a Lebanese-born German man who was detained and tortured by the CIA for five months.

The U.S. government had urged the court to reject the appeal saying that for national security reasons it could not confirm or deny any of the allegations because they were related to the activities of the CIA.

The court said that to make his case, Khaled Al-Masri "would be obliged to produce admissible evidence not only that he was detained and interrogated, but that the defendants were involved in his detention and interrogation in a manner that renders them personally liable to him.

"Such a showing could be made only with evidence that exposes how the CIA organizes, staffs and supervises its most sensitive intelligence operations.

Al-Masri, 43, says he was detained by the CIA for several months in 2004 on suspicion of links to terrorism. He filed suit in December 2005 saying he had been snatched while on a trip in Macedonia, taken to Afghanistan, jailed, beaten and harassed before being set free without charge after five months.

He demanded an explanation and an apology from the United States for his detention, as well as 75,000 dollars in damages.

American Civil Liberties Union director Anthony Romero said the court's decision meant impunity for CIA officials.

"Regrettably, today's decision allows CIA officials to disregard the law with impunity by making it virtually impossible to challenge their actions in court," he said in a statement. "The state secrets doctrine has become a shield that covers even the most blatant abuses of power."

A court in southern Munich in January ordered the arrest of 13 people, thought to be CIA agents, in connection with the alleged kidnapping.

MA/HAR