German states are warning some expatriate residents that Turkey is spying or secretly filming them, a media report says. A leading German politician has accused Ankara of staging "a coup on democracy," Deutsche Welle reports.

Turkey's spy agency has identified hundreds of alleged supporters of exiled Muslim cleric Fethullah Gülen living in Germany, compiling details into a dossier and passing it on to Berlin, a German media report says.

As well as names, the list contains addresses, telephone numbers and photos taken in secret through surveillance cameras, according to the Süddeutsche Zeitung newspaper (link in German). It's said to identify more than 300 people and 200 various clubs, schools, and other institutions with alleged links to Gülen.

Germany's foreign intelligence chief was given the list last month by his Turkish counterpart during the Munich Security Conference. That has allowed authorities across the country to warn those on the list that they have been watched by Turkey.

One German state has gone further, with the state criminal office of North-Rhine Westphalia warning those concerned that possible reprisals await them if they return to Turkish territory.

The Turkish government blames Gülen, who lives in the United States, of orchestrating the unsuccessful military coup attempt last July. Turkey has since launched a massive crackdown on dissent and accused supporters of Gülen, who has denied any part in the insurrection, of being terrorists.