Washington ? A U.S. appeals court says an Algerian protesting his Guantanamo detention deserves a new lower court review — to determine whether he was part of al-Qaida, not just a supporter.

A three-judge panel of the District of Columbia Circuit reversed a lower court decision that Belkacem Bensayah’s imprisonment was legal.

“The evidence upon which the district court relied, in concluding Bensayah supported al-Qaida is insufficient … to show he was part of that organization,” U.S. Circuit Judge Douglas Ginsburg wrote.

He said the lower court needs to determine whether Bensayah “was functionally part of al-Qaida.”

A U.S. district judge found that the government sufficiently presented classified evidence from an unnamed source that Bensayah was a substantial al-Qaida supporter.

Ginsburg questioned that evidence. And he further said the lower court “did not go on to consider whether he was a ‘member’ of al-Qaida or whether his detention was lawful on the alternative ground that he was ‘part of’ that organization.”

The case was decided Monday and released Friday with several classified portions blacked out.

Dozens of terror suspects have argued for their freedom from imprisonment at the U.S. naval base in Cuba where terrorism suspects are held. The Supreme Court has ruled the prisoners have a right to their day in court.

Bensayah was arrested by Bosnian police on immigration charges in late 2001. He was later told that he and five other Algerian men were suspected of plotting to attack the United States Embassy in Sarajevo.

When a Bosnian investigation failed to uncover sufficient evidence of the plot, the men were turned over to the United States and transported to Guantanamo in January 2002.