The Supreme Court on Tuesday terminated a lawsuit from a man who claims he was abducted and tortured by the CIA, effectively endorsing Bush administration arguments that state secrets would be revealed if the case were allowed to proceed.

Khaled el-Masri, 44, alleged that he was kidnapped by CIA agents in Europe and held in an Afghan prison for four months in a case of mistaken identity.

The administration has not publicly acknowledged that el-Masri was detained, and lower courts dismissed his suit after the administration asserted that state secrets would be revealed if the lawsuit were not blocked. The justices rejected his appeal without comment.

The case had been seen as a test of the administration's legal strategy to stop it and several other national security lawsuits by invoking the doctrine of state secrets. Another lawsuit over the administration's warrantless wiretapping program, also dismissed on state secrets grounds, still is pending before the justices.

A coalition of groups favoring greater openness in government says the Bush administration has used the state secrets privilege much more often than its predecessors.

At the height of Cold War tensions between the United States and the former Soviet Union, U.S. presidents used the state secrets privilege six times from 1953 to 1976, according to OpenTheGovernment.org. Since 2001, it has been used 39 times, enabling the government to unilaterally withhold documents from the court system, the group said.

El-Masri's case centers on the CIA's "extraordinary rendition" program, in which terrorism suspects are captured and taken to foreign countries for interrogation. Human rights groups have heavily criticized the program.

President Bush has repeatedly defended the policies in the war on terror, saying as recently as last week that the U.S. does not engage in torture.

El-Masri, a German citizen of Lebanese descent, says he was mistakenly identified as an associate of the Sept. 11 hijackers and was detained while attempting to enter Macedonia on New Year's Eve 2003.

He claims that CIA agents stripped, beat, shackled, diapered, drugged and chained him to the floor of a plane for a flight to Afghanistan. He says he was held for four months in a CIA-run prison known as the "salt pit" in the Afghan capital of Kabul. The lawsuit sought damages of at least $75,000.

The U.S. government has neither confirmed nor denied el-Masri's account. But German Chancellor Angela Merkel has said that U.S. officials acknowledged that El-Masri's detention was a mistake.

El-Masri's account also has been bolstered by European investigations and U.S. news reports. In January, German prosecutors issued arrest warrants for 13 suspected CIA agents who allegedly took part in the operation against him.

El-Masri's lawyers also tried to use a comment by former CIA director George Tenet to show that both the program and el-Masri's case are well-known to the public.

Rather than refuse to comment when asked about El-Masri's claims, Tenet told CNN in May, "I don't believe what he says is true."

The state secrets privilege arose from a 1953 Supreme Court ruling that allowed the executive branch to keep secret, even from the court, details about a military plane's fatal crash.

Three widows sued to get the accident report after their husbands died aboard a B-29 bomber, but the Air Force refused to release it claiming that the plane was on a secret mission to test new equipment. The high court accepted the argument, but when the report was released decades later there was nothing in it about a secret mission or equipment.

The case is El-Masri v. U.S., 06-1613.