Munich prosecutors press the U.S. for the arrest of 13 suspected CIA agents wanted in the alleged kidnapping three years ago of a German citizen.
Arrest warrants were issued at the end of January for the unidentified agents, accused of the wrongful imprisonment of Khaled al-Masri and causing him serious bodily harm.
Prosecutor August Stern would not comment whether the U.S. had responded to the initial warrants, but did confirm a report that his office had recently sent a second request for the arrest of the agents.
"We are doing everything that we can do," he said.
The U.S. Embassy in Berlin refused to comment.
The initial arrest warrants came just ahead of a visit by German Foreign Minister Frank-Walter Steinmeier to Washington to meet with U.S. Secretary of State Condoleezza Rice.
At that time, State Department spokesman Sean McCormack confirmed the U.S. Justice Department was handling the German warrants, but did not provide further details.
Al-Masri, a German citizen of Lebanese descent, maintains he was abducted in December 2003 at the Serbian-Macedonian border and flown by the CIA to a detention center in Kabul, Afghanistan, where he was abused.
He says he was released in Albania in May 2004, and that his captors told him he was seized in a case of mistaken identity.
Human rights campaigners have seized on al-Masri's story to press the United States to stop flying terrorism suspects to countries other than the U.S. where they could face abuse _ a practice known as "extraordinary rendition." In a separate case, Italy has issued arrest warrants for alleged CIA agents.
Rice and other U.S. officials have declined to address the case. However, German Chancellor Angela Merkel has said the United States has acknowledged making a mistake with al-Masri.