BERLIN -- German police on Tuesday detained the country's former head of its foreign-intelligence service on suspicion of espionage and attempted treason in one of the biggest scandals to engulf the spy agency since its creation in the mid-1950s.

August Hanning, who led the Federal Intelligence Service, or BND, from 1998 to 2005, was arrested under suspicion of illegally obtaining classified information for years and, in at least one case, passing it on to a foreign intelligence agent, Germany's General Federal Prosecutor said.

A lawyer for Hanning couldn't be immediately contacted for comment.

Police also arrested Hanning's former bureau chief, only identified as Manfred D., who allegedly passed on classified information to Hanning for more than a decade in his function as bureau chief for subsequent BND presidents.

The arrest of Hanning marks the first time a former BND chief has been detained.

The agency has faced criticism for failing to predict Russia's full-scale invasion of Ukraine. The agency's then president, Bruno Kahl, now Germany's ambassador to the Vatican, was in Kyiv on the day of the invasion in 2022 and had to be exfiltrated by road.

Several BND workers, including some senior ones, were detained in recent years on suspicion of passing classified information to foreign powers, including Russia.

The arrest of Hanning is a significant setback for Chancellor Friedrich Merz, who appointed Martin Jäger, the agency's current head, with a mandate to restore its reputation. Jäger is overseeing the BND's transformation from a pure information-gathering and analysis outfit into a harder-hitting secret service with expanded powers, including the ability to strike back following cyberattacks.

The bill beefing up the powers of the BND and the BfV domestic intelligence agency is currently making its way through parliament. News of the arrest comes just one day after Jäger and the domestic and military intelligence heads faced parliament for a regular question-and-answer session.

Hanning faces possible charges of treasonous espionage, illegally obtaining state secrets, attempted treason and espionage, the prosecutor's office said. Manfred D. is suspected of aiding and abetting attempted treason and treasonous espionage.