Turkish President Recep Tayyip Erdogan on Friday told the EU and US to "mind your own business" after the West expressed alarm over the growing crackdown against suspected coup plotters.

Turkish President Recep Tayyip Erdogan on Friday told the EU and US to "mind your own business" after the West expressed alarm over the growing crackdown against suspected coup plotters, as a court placed 17 journalists under arrest.

Turkey has detained more than 18,000 people over the coup which Ankara blames on the US-based preacher Fethullah Gulen, with the relentless crackdown sparking warnings from Brussels that its EU membership bid may be in danger.

"Some people give us advice. They say they are worried. Mind your own business! Look at your own deeds," Erdogan said in a speech at his presidential palace.

"Not a single person has come to give condolences either from the European Union... or from the West," said Erdogan.

"And then they say that 'Erdogan has got so angry'!" he fumed.

"Those countries or leaders who are not worried about Turkey's democracy, the lives of our people, its future -- while being so worried about the fate of the putschists -- cannot be our friends."

Erdogan vowed to take all steps "within the limits of the law" as Turkey seeks legal retribution for the perpetrators of the coup.

A Turkish official said 3,500 of those detained have now been released after questioning.

EU enlargement commissioner Johannes Hahn said he needed to see "black-and-white facts about how these people are treated".

"And if there is even the slightest doubt that the (treatment) is improper, then the consequences will be inevitable," he told German daily Sueddeutsche Zeitung.

Turkey has also targeted journalists accused of links to Gulen, causing further international alarm.

Twenty-one detained suspects Friday appeared in front of a judge in Istanbul to decide whether to remand them in custody.

After a hearing lasting to midnight, four were freed but 17 placed under arrest ahead of trial, charged with "membership of a terror group", the state-run Anadolu news agency said.

Those held include the veteran journalist Nazli Ilicak as well as the former correspondent for the pro-Gulen Zaman daily Hanim Busra Erdal, it added.