"It is just not acceptable. It is a clear breach of international law," Struck, who was defence minister from 2002 until 2005, told Phoenix TV.

Struck said the government and the Bundestag lower house of parliament "would not accept that a state believed it had the right to say that it was not interested in international law and human rights."

Foreign Minister Frank-Walter Steinmeier told parliament on Wednesday that Germany had known nothing about the abduction of Lebanese-born Masri until after he was released in 2004.

Masri last week filed a lawsuit against the US Central Intelligence Agency in a US federal court, alleging that he was wrongfully abducted and abused as a prisoner.

Chancellor Angela Merkel said after meeting US Secretary of State Condoleezza Rice in Berlin last week that Washington had accepted that it had mistakenly detained Masri.

His case has fuelled the controversy over alleged prisons run by the CIA and the illegal transportation of prisoners across international borders.