His case has drawn worldwide attention to the CIA's extraordinary rendition program in which terrorism suspects are sent from one foreign country to another for interrogation. Human rights groups have strongly criticized the program.

Masri's case sparked outrage in Germany and prompted a parliamentary inquiry to find out what authorities might have known about U.S. renditions.

Masri's attorneys from the American Civil Liberties Union challenged what they called the Bush administration's increased invoking of national security secrets to prevent any judicial inquiry into serious allegations of misconduct.

The administration also has asserted the so-called state secrets privilege in an effort to dismiss the lawsuits over the warrantless domestic spying program that Bush created after the September 11 attacks.

'CENTRAL FACTS NOT STATE SECRETS'

Masri's allegations have been widely reported by the news media. "The central facts of this case are not state secrets and do not become so simply because the government insists otherwise," Ben Wizner of the ACLU wrote in the appeal.

Masri's lawsuit, which sought damages of at least $75,000, was brought against former CIA Director George Tenet, three private aviation companies and 20 unnamed employees of the CIA and the companies.

The Supreme Court sided with the administration and rejected the appeal without any explanation or recorded dissent.

Masri said he was abducted by Macedonian authorities on December 31, 2003, while on vacation. After 23 days, he was handed over to a CIA team and flown to a CIA-run secret prison near Kabul, Afghanistan, he said.

Masri said he was beaten, interrogated and held as a terrorism suspect, even though CIA officials quickly determined his innocence. He said he was flown to Albania and released on May 28, 2004.

A federal judge and then a U.S. appeals court dismissed the lawsuit because it threatened to expose government secrets, including how the CIA supervises its most sensitive intelligence operations.

The Supreme Court formally recognized the state secrets privilege in a 1953 ruling. The ACLU's attorneys said the court has not revisited the decision in more than 50 years and urged the justices to re-examine it.

The CIA has never acknowledged any role in Masri's detention. The Bush administration opposed Masri's appeal.

Administration attorneys said lower courts applied "settled legal principles to the highly classified facts of this case" and that further review by the Supreme Court was unwarranted.