Mamoun Darkazanli, 46, a Syrian-German dual national, was taken into custody in Hamburg on Friday on a Spanish warrant and is being held for possible extradition, city judicial spokeswoman Sabine Westphalen told The Associated Press.
Darkazanli was questioned by German police shortly after the Sept. 11, 2001 attacks on the United States when it emerged that three of the suicide hijackers lived and studied in Hamburg. He was freed for lack of evidence and continued to live in the German port city.
His Hamburg-based trading company was has been labeled a front for terrorism by U.S. President George W. Bush.
Spanish authorities allege that Darkazanli was "one of the key figures of the al Qaeda terror network" and "the permanent contact person and assistant of Osama bin Laden in Germany," Hamburg authorities said in a statement.
He is accused of giving logistical and financial support to the network in Spain, Germany and Britain since 1997, the statement said.
Darkazanli, a Syrian native who has lived in Hamburg for years, faces up to 12 years in prison in Spain if convicted of charges of membership in a terrorist organization.
German authorities arrested him because he was a flight risk, the statement said. It did not elaborate.
Darkazanli did not respond to the charges after his arrest, but said he would contest extradition, the statement said.
Darkazanli is alleged to have been involved in the purchase of a ship for al Qaeda leader bin Laden, handling administrative details and paying bills. He also allegedly traveled to Kosovo in late 2000 on an al Qaeda mission, Hamburg authorities said.
He was among 35 suspects — including bin Laden himself — who were indicted in September 2003 by Baltasar Garzon, a Spanish judge investigating al Qaeda.