German police have arrested the country’s former foreign intelligence chief on suspicion of espionage and attempted treason, in one of the biggest scandals to hit the spy agency since its founding.

August Hanning, 80, who led the Federal Intelligence Service (BND) from 1998 to 2005, was detained on Tuesday. Prosecutors say his former chief of staff, identified as Manfred D., passed him about 2,000 classified documents over more than a decade, until at least mid-2022.

Hanning is accused of using the material to prepare an analysis for a foreign intelligence officer and of passing political information to a second foreign service. Der Spiegel reported that one contact was Wang Jianzheng, a retired Chinese army major general. A court on Wednesday ordered Hanning to remain in pretrial detention.

Hanning is the first former BND president ever detained. Lawmakers warned the case could damage Germany’s ties with allied intelligence services.

The scandal lands as Berlin seeks to expand the agency’s powers to counter threats from Russia, making the timing especially damaging.