The federal prosecutors' office said the morning raids in the states of North Rhine-Westphalia and Rheinland-Palatinate were carried out to collect evidence, and no arrests were made.
The unidentified targets are suspected of spying on supporters of US-based cleric Fethullah Gulen, who is accused by the Turkish government of orchestrating a July 15 coup.
Prosecutors say the four men affiliated with the DITIB, the union of Turkish-Islamic cultural organisations in Germany, are suspected of passing the information on to the Turkish consulate in Cologne.
Last week, when an official of Germany's domestic intelligence agency said that 13 imams affiliated with DITIB had sent the names of alleged supporters of Gulen to the Turkish government's Office for Religious Affairs, Diyanet, the union said it was not involved and that Diyanet supervised imams directly.
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Following the raids, Justice Minister Heiko Maas said the government expects "DITIB to promptly and completely explain the allegations."
"Whoever uses Islam as a cover for espionage cannot rely (for protection) on the freedom of religion," he said. "If the suspicion that some DITIB imams were spying is confirmed, the organisation must be seen, at least in parts, as a long arm of the Turkish government."
Austrian Greens Parliamentarian Peter Pilz said memos from the Turkish Embassy in Vienna and the Turkish Consulate in Salzburg showed ATIB, the Austrian equivalent to DITIB, sending in reports on Gulen-backed organizations, with the information then forwarded to Ankara.
Pilz spoke of a "global spying network," saying his team was working on publishing similar documents from 30 other countries in Europe, Africa and Asia.
The matter came up when German Chancellor Angela Merkel visited Ankara at the beginning of February, and Merkel said that "confusion must not arise here."
She stressed that she wants people of Turkish origin in Germany "to be able to have access to their imams. So confusion or this feeling that people here are being observed or spied on must be dispelled from the start.
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