The warning from the Council of Europe — which is a separate organization to the European Union and is based in Strasbourg, France — is the latest in a series of warning to Turkey over alleged human rights abuses and clampdowns on press freedoms and opposition parties by Erdogan's government.
The latest intervention is possibly the sternest warning, after months during which Erdoğan has increased his grip on power as his country faces continuing battles between government forces and Kurdish opposition forces, while also living on the sidelines of the conflict in Syria and struggling to deal with the consequential migrant crisis.
In the latest clampdown on the media, the editor of the opposition Cumhuriyet newspaper and several editorial staff have been arrested and detained. They are accused of seeking to precipitate the coup through "subliminal messages" in their columns before it happened, according to the state-run Anadolu agency.
Council of Europe of Secretary General Thorbjorn Jagland said: "It is highly questionable if the raid against Cumhuriyet can be justified as a proportionate measure, even under the state of emergency. I am also concerned about the closure of 15 Kurdish media outlets through a decree-law.
"I should like to recall that the European Convention on Human Rights continues to apply in Turkey even during the state of emergency. Careful distinction must be made between violent or terrorist acts and expressions of opposition or strong criticism to the Government. Freedom of expression constitutes one of the essential foundations of a democratic society."
"If the state of emergency is used too excessively, Turkey risks a flood of cases at the European Court of Human Rights (ECHR)."
Although the Council of Europe is not part of the EU, the invocation of the ECHR will give opponents of the EU-Turkey migrant deal — an attempt to encourage Turkey to stem the flow of migrants into Europe in return for accelerated accession to full EU membership — ammunition to deal, which already faces still opposition.