The federal prosecutor's office in Germany says police have conducted a series searches across the country in connection with investigations into 10 suspected Iranian spies.
However, officials said no arrests were made as a result of the January 16 raids.
A spokesman for the federal prosecutor, Stefan Biehl, said the raids were prompted by information received from Germany's domestic intelligence service, the Office for the Protection of the Constitution (BfV), which is in charge of Germany's counterespionage operations.
Biehl said the suspects were thought to have "spied on institutions and persons in Germany on behalf of an entity associated with Iran."
A German weekly magazine, Focus, reported that the suspects were thought to have been carrying out "secret service activities" by spying on Israeli citizens in Germany.
According to Focus, the raids were carried out at buildings in Berlin as well as the states of Baden-Wuerttemberg, North Rhine-Westphalia, and Bavaria.
Prosecutors declined to comment on reports that the suspects were members of Iran's Quds Force, a special unit of the Islamic Revolutionary Guards Corps (IRGC) responsible for carrying out clandestine operations outside of Iran.
The Quds Force is commanded by IRGC Major General Qassem Soleimani and reports directly to Supreme Leader Ayatollah Ali Khamenei.
In 2007, the U.S. Treasury Department designated the Quds Force as a supporter of terrorism for sending weapons and ammunition to the Taliban in Afghanistan, as well as weapons, funding, and guidance to "other terrorist organizations" -- including Lebanon's Hizballah, Hamas, Palestinian Islamic Jihad, and the general command of the Popular Front for the Liberation of Palestine.
In December, Germany's government protested to the Iranian ambassador in connection with the conviction of a Pakistani man who was serving as an Iranian agent.
Berlin's Superior Court sentenced 31-year-old Mustufa Haidar Syed-Naqfi to four years and three months in prison on charges of "working for a foreign intelligence service."
The court found he spied "against Germany" and France on behalf of the Quds Force by compiling information about possible attack targets in Germany -- German lawmaker Reinhold Robbe, who previously headed the German-Israeli Association, and a French-Israeli economics professor.
Investigators found detailed dossiers about the men and their daily routines, with hundreds of photos and video clips documenting their homes and workplaces, access routes to them, and information about security guards, surveillance cameras, and nearby police stations.
Germany's Foreign Ministry said Iranian Ambassador Ali Majedi was summoned and told that "spying on people and institutions with a particular relationship to the state of Israel on German soil is a blatant violation of German law."
With reporting by AP, dpa, and Focus