Turkey was warned yesterday that it could face international isolation, including suspension from Nato, as world leaders told the country's authoritarian president not to overplay his hand after the failed coup.

After a night which saw thousands arrested or dismissed from their posts on suspicion of involvement in the putsch, John Kerry, the US secretary of state, led calls from the US and the EU for restraint.

President Recep Tayyip Erdogan’s widespread purge has reinforced worries in the West about democratic regression in Turkey.

Mr Kerry, speaking in Brussels, stressed that Nato had a requirement when it came to democracy and "will measure very carefully what is happening".

“A lot of people have been arrested and arrested very quickly,” he said. Mr Kerry added that “the level of vigilance and scrutiny is obviously going to be significant in the days ahead".

Turkey is already at odds with Washington over the extradition of the exiled Islamic cleric accused by Mr Erdogan’s government of masterminding the coup.

Ankara has demanded that Fethullah Gulen, a longtime foe of the president who is living in Pennsylvania and denies the claims, be handed over for trial. Mr Kerry said they must first provide evidence.

A decision to oust the country of almost 80 million from Nato would not be taken lightly. Turkey has the second-largest army in the security alliance and plays a vital role in the war against Islamic State of Iraq and the Levant, as well as in stemming the tide of refugees.

European Union officials also warned yesterday that talks on Turkey's bid to join the bloc would end if the country restored the death penalty, as Mr Erodgan has proposed to do to deal with the plotters.

Turkey has not executed anyone since 1984 and capital punishment was legally abolished in 2004 as part of its bid to join the EU.

Johannes Hahn, the EU commissioner dealing with its long-stalled ascension bid, accused Mr Erodgan of having planned the purge of opponents before the coup, as part of a bid to consolidate power.

"The fact the [arrest warrant] lists were available already after the event indicates that this was prepared and at a certain moment should be used," he said.

Within hours of the revolt’s failure on Friday night, which left 290 dead and 1,400 wounded, more than 6,000 members of the military were rounded up and detained.

Yesterday the government arrested a further 103 generals, dismissed 9,000 civil servants, 8,000 police officers, a third of Turkey’s 80 provincial governors, as well as a huge swathe of the judiciary that has sometimes blocked Mr Erdogan. All were accused of links to Mr Gulen.

A list was also circulating of high-profile journalists earmarked for arrest in the coming days.

The political affiliation of the leaders of the coup is still unclear, though President Erdogan was quick to blame Mr Gulen’s moderate Muslim “Hizmet” movement, which his government commonly calls “the parallel state structure”. The group has some support among the Anatolian middle class.

The military officials accused of masterminding the failed coup were yesterday paraded on camera with their hands bound and ordered to give their name and rank before being taken to be interrogated.

Among them was “leading Gulenist” Akin Ozturk, head of the air force until 2015 and a member of the High Military Council (YAS), who according to state media confessed to prosecutors his role as one of the chief plotters, but this was later contradicted by private broadcasters.

“No matter who they arrest now, they are all labeled as Gulenists,” a commentator with the daily Turkish newspaper Zaman said.

“I do not think even the military personnel detained are all supporters, let alone the others who were sacked or arrested.

“Most Gulen followers had already been purged from bureaucracy, judiciary and particularly from security apparatus,” he said, suggesting the government was using the revolt as an excuse to eliminate all other sources of dissent and opposition.

One government official, defending the widespread crackdown, said: “I understand that the numbers [of arrests] seem excessive. But right now this is about preventing the next wave of attacks against civilians and government buildings.

“This is a very large organisation. They themselves claim to have several million members and contributors, and they have been penetrating civilian and military bureaucracy for decades.

“Obviously, the courts will consider evidence and reach their verdicts,” he said.

Critics questioned how independent the court system will be after the purge of some of its most senior judges.