The United States and European Union on Monday sternly warned Turkey to respect the rule of law after President Recep Tayyip Erdogan's government launched a massive crackdown following the failed coup.
Germany and the EU also said any move by Turkey to reinstate the death penalty for the coup plotters would derail Ankara's long-stalled membership bid.
US Secretary of State John Kerry and EU foreign policy chief Federica Mogherini said in Brussels that Friday's attempted putsch was "no excuse" for excessive action, as Turkish authorities said they had arrested over 7,500 people and sacked more than 9,000.
"We will certainly support bringing the perpetrators of the coup to justice but we also caution against a reach that goes well beyond that," Kerry told a press conference with Mogherini.
The EU and US "urge the government of Turkey to uphold the highest standards of respect for the nation's democratic institutions and the rule of law", he added.
Mogherini said as EU foreign ministers met that the "rule of law has to be protected in the country, there is no excuse for any steps that take the country away from that", adding that it was "for the sake of the country."
The EU commissioner dealing with Turkey's long-stalled bid for membership of the bloc said it appeared that the government had already prepared a list before the coup of people to be rounded up.
"I mean, (that) the lists are available already after the event indicates that this was prepared and at a certain moment should be used," enlargement commissioner Johannes Hahn told reporters.
German Chancellor Angela Merkel's spokesman denounced "revolting scenes of caprice and revenge against soldiers on the streets" after disturbing pictures emerged of the treatment of some detained suspects.
After Erdogan said Sunday that Turkey would consider a return of capital punishment, spokesman Steffen Seibert said such a move "would mean the end of EU membership talks".
Mogherini was quick to echo the German position.
"Let me be very clear... no country can become an EU state if it introduces the death penalty," she said.
Turkey has called on Washington to hand over exiled Muslim cleric Fethullah Gulen, Erdogan's chief foe, over the failed coup, but Kerry said Ankara must produce proof.
He said he had told Turkey's foreign minister "to make certain that in whatever portfolio and request they send us, they send us evidence, not allegations".
Turkey's attempts to join the 28-nation European Union have been hobbled in recent years by concern over the increasingly authoritarian Erdogan's record on human rights and press freedom.
But the EU agreed to speed up its membership bid and give visa-free travel to Turks as part of a migrant crisis deal in which Ankara agreed to take back people landing in the Greek islands.
French Foreign Minister Jean-Marc Ayrault said that "the rule of law must prevail".
"France has condemned the coup, you can't accept the military taking power," he said. "At the same time we have to be vigilant that the Turkish authorities don't put in place a system which turns back democracy."
Belgian Foreign Minister Didier Reynders also urged restraint, saying: "It's normal to punish those involved in the coup, but it's (also) normal to ask for respect for the rule of law."