Prosecutors are investigating claims by Khaled al-Masri, a German citizen of Lebanese descent, that he was seized in Macedonia on Dec. 31, 2003, and taken by CIA agents to Afghanistan. He says he was abused in captivity before he was released in Albania in May 2004.
German officials are under pressure to explain what they knew of the case, what they passed on to prosecutors and whether they pressed U.S. officials for information. Ministers insist they only heard of the case after al-Masri's release.
Justice Minister Brigitte Zypries faced questions about the case on Wednesday before a parliamentary committee.
Speaking later to reporters, Zypries said her ministry only learned of the case in June 2004. She said her officials had done all "that was necessary in a legal process," such as helping investigators request legal assistance from abroad.
She also said federal prosecutors had looked at the case but decided there was no evidence for a politically motivated kidnapping. State prosecutors in Munich are currently investigating.
Interior Minister Wolfgang Schaeuble also appeared before a parliamentary panel and Foreign Minister Frank-Walter Steinmeier, who was then-Chancellor Gerhard Schroeder's chief of staff at the time of the alleged abduction, was to appear before a similar body on Thursday.
Lawmakers were to question the government at a lower house session later Wednesday.
New Chancellor Angela Merkel said last week after meeting U.S. Secretary of State Condoleezza Rice that Washington had accepted making a "mistake" with al-Masri — something U.S. officials have denied.
Al-Masri's case has drawn extra scrutiny amid allegations that the CIA ran secret prisons for Al Qaeda suspects in Eastern Europe and used clandestine flights to ship prisoners through European airports.
Merkel's conservative party and their coalition partners, Schroeder's Social Democrats, are resisting opposition calls for a full parliamentary investigation.