The United States and the European Union warned Turkey on Monday to show restraint in its response to a failed military coup last week, worrying that Ankara's retaliatory measures are going too far.
Thousands of people have been arrested since the foiled coup, while thousands more have been removed from their posts - most controversially, judges.
"We will certainly support bringing the perpetrators of the coup to justice, but we also caution against a reach that goes well beyond that," US Secretary of State John Kerry said after meeting EU foreign ministers in Brussels.
"We have been the first to stress the need ... for having the legitimate institutions protected against the attempt of a coup. This is no excuse to take the country away from fundamental rights and rule of law," EU foreign policy chief Federica Mogherini added.
Punishment against the coup plotters must not include "measures that could lead to an authoritarian state," French Foreign Minister Jean-Marc Ayrault said in Brussels, while Germany's Frank-Walter Steinmeier called for proportionality in Turkey's response.
The EU's commissioner for neighbourhood policy, Johannes Hahn, suggested that the Turkish government had long been planning action against opponents.
"That the lists are available already after the event indicates that this was prepared, that at a certain moment it should be used," he said in Brussels, adding that the arrests of judges was "exactly what we have feared."
The EU also piled pressure on Ankara not to reintroduce the death penalty following the foiled coup, warning that this would derail the country's long-standing efforts to join the European bloc.
Capital punishment is forbidden by the charter of fundamental rights of the EU, which is a lead campaigner for its abolition around the world.
Turkish President Recep Tayyip Erdogan nevertheless said on Sunday that he would discuss with opposition parties in parliament the possibility of capital punishment for those who carried out the failed coup attempt.
The death penalty has not been used in Turkey since 1984 and was abolished in 2004.
"No country can become an EU member state if it introduces the death penalty," Mogherini warned.
"We categorically reject the death penalty," German Chancellor Angela Merkel's spokesman, Steffen Seibert, added in Berlin. "A country that has the death penalty cannot be an EU member."
The EU's foreign ministers are expected to issue a statement on the situation in Turkey later Monday.
"We will have to be very firm today," Belgian Foreign Minister Didier Reynders predicted.
The coup attempt on Friday night by a group within the Turkish armed forces left 290 people dead - including more than 100 alleged mutineers - and more than 1,100 injured.
Erdogan has blamed Fethullah Gulen, a US-based, Turkish-born preacher and one-time ally turned rival accused of running a "parallel state."
Kerry said Monday that Turkey has not yet formally requested Gulen's extradition.
The US would do "nothing whatsoever to stand in the way of a legitimate process" respecting its extradition treaty with Turkey, Kerry said. But he also warned Ankara to send "evidence, not allegations," if it files an extradition request.