U.S. government officials contacted by AP acknowledged questioning prisoners in Ethiopia. But they said American agents were following the law and were fully justified in their actions because they are investigating past attacks and current threats of terrorism.

The prisoners were never in American custody, said an FBI spokesman, Richard Kolko, who denied the agency would support or be party to illegal arrests. He said U.S. agents were allowed limited access by governments in the Horn of Africa to question prisoners as part of the FBI's counter-terrorism work.

Others disagree and say the U.S. has been instrumental in causing the arrest of the suspects.

John Sifton, a Human Rights Watch expert on counter-terrorism, went further. He said in an e-mail that the United States has acted as "ringleader" in what he labeled a "decentralized, outsourced Guantanamo."

Details of the arrests, transfers and interrogations slowly emerged as AP and human rights groups investigated the disappearances, diplomats tracked their missing citizens and the first detainees to be released told their stories.