Turkish President Tayyip Erdogan accuses a network of schools, charities and businesses led by Gulen, and built up in Turkey and abroad over decades, of infiltrating state institutions and orchestrating the failed coup.

Authorities in Turkey have arrested or suspended tens of thousands of police, troops, officials, judges and civil servants because of their alleged links to Gulen’s movement.

Citing classified documents, Spiegel said Turkey’s secret service had asked Germany’s foreign intelligence agency (BND) for help in rounding up Gulen supporters in Germany.

The magazine said the Turkish secret service wanted the BND to use its influence to spur German lawmakers into taking action against Gulen supporters and extraditing them to Turkey.

A spokesman for the BND said the agency only reported on the operative aspects of its work to the German government and the responsible authorities in the lower house of parliament.

A Turkish presidency official said: “It’s not our policy to comment on intelligence operations. However, we expect all our friends and allies to assist Turkey’s efforts to hold FETO operatives accountable for their crimes.” FETO is an abbreviation standing for the “Gulenist Terror Group” which is how Ankara refers to Gulen’s movement.

Germany is home to a three-million strong Turkish community and concern is growing that tensions between Erdogan backers and Gulen supporters are spilling over onto German soil.

Erdogan backers have demonstrated in several German cities since July’s attempted putsch, shops have been boycotted by political rivals and hate mail has been sent to anti-Erdogan politicians.

Turkish Prime Minister Binali Yildirim said on Saturday Ankara would put its domestic and external intelligence operations under an umbrella structure to allow better coordination and help prevent another coup attempt.