BERLIN (Reuters) - Germany has warned citizens visiting Turkey to be extra cautious about their social media feeds in response to a spate of cases of Germans arrested for online criticism of Turkish President Tayyip Erdogan’s government.

FILE PHOTO: Supporters of Turkish President Tayyip Recep Erdogan rally after the official inauguration of the Cologne Central Mosque in Cologne, Germany, September 29, 2018. REUTERS/Wolfgang Rattay/File Photo

The updated travel advice, published by the Foreign Ministry on Tuesday, highlights how Berlin’s attempts to repair relations with Ankara have so far delivered little for dozens of German citizens imprisoned there since the failed coup in 2016.

Hundreds of people died in the overnight putsch attempt, which was followed by a vast security crackdown involving thousands of arrests of alleged followers of exiled cleric Fethullah Gulen, some of whom are German-Turkish dual citizens.

Erdogan’s government has accused the U.S.-based Gulen of orchestrating the coup, something he has repeatedly denied.

“Arrests and prosecutions frequently related to social media posts that were critical of the government,” read the new travel advice. “In some cases merely ‘liking’ another’s post of that nature is enough,” it adds.

With Germany home to 3 million people of Turkish background, relations been the two countries have always been complicated, but they hit rock bottom in the wake of the post-coup round-up.

A flurry of diplomatic activity, including a state visit by Erdogan to Germany, has so far yielded little in the way of reduced tensions, with Berlin deeply concerned at Ankara’s influence over Germany’s Turkish community.

The ministry added that even private comments could be risky. “Non-public comments on social media can be forwarded to Turkish authorities via denunciations,” it said. “A conviction for ‘insulting the president’ or ‘spreading terrorist propaganda’ can lead to many years’ imprisonment.”

Social media have become the primary platform for political opposition in Turkey, where traditional media are saturated with positive coverage of Erdogan and his ministers.

Turkish authorities have detained people who criticized a military operation in Syria on social media and those who posted comments about the economy “in a provocative way”, as the lira tumbled against the dollar this year.

Germany is has a large and growing community of exiled critics of Erdogan, many of whom Ankara wants to see extradited on terrorism charges. Some complain they are subject to surveillance by Turkey’s intelligence services.