The German Interior Ministry said Thursday it is questioning 20 individuals for allegedly spying on followers of an exiled preacher accused of being responsible for the attempted coup in Turkey in 2016.

"At the moment, a total of 20 accused and persons unknown are under investigation over suspicions that they worked as secret service agents on the orders of the Turkish government, and spied on followers of the Gulen movement," said Germany's interior ministry in a response to a query from Linke party lawmaker Sevim Dagdelen.

The German Interior Ministry told Associated Press news agency that it was investigating 16 known suspects as well as four others. It would not say how many were still in Germany.

German prosecutors said in March they were analyzing claims that Turkish agents were spying on followers of Islamic cleric Fethullah Gulen, who Turkish President Recep Tayyip Erdogan blames of being behind the attempted coup in Turkey last year which left hundreds dead. A raid on four homes of Islamic clerics affiliated with the union of Turkish-Islamic cultural organizations in Germany (DITIB) was conducted by Germany in February. They were believed to have passed information about Gulen followers in Germany to the Turkish consulate.

It is unknown whether any of the 20 people accused by the German Interior Ministry are Islamic clerics or imams.

Gulen is currently living in the US in self-imposed exile and has denied involvement with the failed coup. In the wake of the coup tens of thousands of Turks have been arrested or removed from state positions in Turkey.

Germany and Turkey in war of words

Germany's relationship with NATO ally Turkey turned sour after the attempted coup. Germany condemned the crackdown on alleged coup conspirators by Erdogan, while Erdogan has made wild accusations against Germany, including one of Germany becoming a "haven for terrorists."

Turks are currently voting on a referendum to give Erdogan more powers while Turkey is in a state of emergency. Germany blocked campaign events by Turkish ministers in March, which lead Erdogan to accuse Germany of using "Nazi" methods to silence supporters. Germany condemned the accusation.

kbd/kl (AFP, AP)