ISTANBUL/ANKARA (REUTERS) - Turkey widened a crackdown on suspected supporters of a failed military coup on Sunday (July 17), taking the number of people rounded up in the armed forces and judiciary to 6,000, and the government said it was in full control of the country and economy.

Supporters of President Tayyip Erdogan gathered in front of his Istanbul home to call for the plotters to face the death penalty, which Turkey outlawed in 2004 as part of its efforts to join the European Union. "We cannot ignore this demand," Erdogan told the chanting crowd. "In democracies, whatever the people say has to happen."

Pictures on social media showed detained soldiers stripped from the waist up, some wearing only their underpants, handcuffed and lying packed together on the floor of a sports hall where they were being held in Ankara.

One video on Twitter showed detained generals with bruises and bandages. Akin Ozturk, head of the air force until 2015 and identified by three senior officials as one of the suspected masterminds of the coup plot, was among those held.

The Foreign Ministry raised the death toll to more than 290, including over 100 rebels, and said 1,400 people were hurt.

The violence shocked the nation of almost 80 million, once seen as a model Muslim democracy, where living standards have risen steadily for more than a decade and where the army last used force to stage a successful coup more than 30 years ago.

It also shattered fragile confidence among Turkey's allies about security in the Nato country, a leading member of the US-led coalition against the Islamic State (ISIS) group. Turkey had already been hit by repeated suicide bombings over the past year and is struggling to contain an insurgency by Kurdish separatists.

With expectations growing of heavy measures against dissent, European politicians warned Erdogan that the coup attempt did not give him a blank cheque to disregard the rule of law, and that he risked isolating himself internationally as he strengthens his position at home.

Broadcaster NTV cited Justice Minister Bekir Bozdag as saying that more arrests were expected on top of the 6,000 people already detained.

Authorities have rounded up nearly 3,000 suspected military plotters, ranging from top commanders to foot soldiers, and the same number of judges and prosecutors after forces loyal to Erdogan crushed the attempted coup on Saturday.

Among those arrested is General Bekir Ercan Van, commander of the Incirlik air base from which US aircraft launch airstrikes on ISIS militants in Syria and Iraq, an official said. Erdogan's chief military assistant was also detained, broadcaster CNN Turk said.

Erdogan told crowds on Sunday that the coup attempt had been put down by the "national will", blaming "those who cannot bear the unity of our country and are under the orders of masterminds to take over the state".

He frequently refers to "masterminds" who he says are bent on breaking up Turkey, in what appears to be a veiled reference to the West in general, and more specifically, the United States.

On Saturday, Labour Minister Suleyman Soylu told broadcaster Haberturk he believed Washington was behind the coup attempt. US Secretary of State John Kerry described public suggestions of a US role as "utterly false", and said on Sunday that Washington had no intelligence of the coup before it began.

The Pentagon also announced on Sunday that operations from Turkey by the US-led coalition against ISIS had resumed after Ankara reopened its air space, which had been closed during the coup attempt.

However, US facilities were still operating on internal power sources after Turkey cut off the mains supply to the base. Kerry said the difficulty for US planes using Incirlik may have been a result of Turkish aircraft flown in support of the coup using the base to refuel.

'PARALLEL STRUCTURE'

The crackdown intensifies a long-standing push by Erdogan to root out the influence of followers of US-based cleric Fethullah Gulen.

Erdogan accuses followers of Gulen, who was once an ally but is now his arch-enemy, of trying to create a "parallel structure" within the courts, police, armed forces and media with an aim to topple the state.

The cleric has denied this and said he played no role in the attempted coup, denouncing it as an affront to democracy.

Erdogan said Turkey's justice and foreign ministries would write to Western governments to demand the return of Gulen's supporters from those countries.

Kerry said he had no evidence that Gulen was behind the plot to seize power, and he urged Turkish authorities to compile evidence as rapidly as possible so the US could evaluate whether he should be extradited to Turkey.

Even before the coup attempt was over, Erdogan promised a purge of the armed forces. "They will pay a heavy price for this," he said. "This uprising is a gift from God to us because this will be a reason to cleanse our army."

At a rally late on Saturday, his supporters demanded that the coup leaders be executed.

"Let's hang them!" chanted the crowd in Ankara's central Kizilay square. Erdogan told them that parliament may consider a proposal to bring back the death penalty, which has been abolished.

Erdogan's critics say he will use the purge to create a pliant judiciary, eliminating any dissenting voices in the courts.

Some European politicians have expressed their unease about developments since the coup attempt.

"(The coup attempt) is not a blank cheque for Mr Erdogan. There cannot be purges, the rule of law must work," said French Foreign Minister Jean-Marc Ayrault.

Ayrault told France 3 television that European Union ministers would reiterate on Monday when they meet in Brussels that Turkey - which has applied to join the bloc - must conform to Europe's democratic principles.

European Commissioner Guenther Oettinger said Erdogan would move Turkey away from the core values represented by the EU and the Nato defence alliance - of which it is a long-standing member - if he decided to use the attempted coup to restrict basic democratic rights further.

"He would strengthen his position domestically, but he would isolate himself internationally," Oettinger, an ally of German Chancellor Angela Merkel, told Welt am Sonntag newspaper.

Some European politicians are also expressing concern about the future of a deal between the EU and Ankara that has helped to slow numbers of migrants crossing from the country to neighbouring Greece.

GULEN DENIAL

A successful overthrow of Erdogan, who has ruled the country since 2003, would have marked another seismic shift in the Middle East, five years after the Arab uprisings erupted and plunged Turkey's southern neighbour Syria into civil war.

But the failed attempt could still destabilise the US ally, which lies between Europe and the chaos of Syria.

Gulen said the attempted overthrow may have been staged to justify a crackdown.

"As someone who suffered under multiple military coups during the past five decades, it is especially insulting to be accused of having any link to such an attempt. I categorically deny such accusations," Gulen said in a statement.

Erdogan's Islamist-rooted AK Party has long had strained relations with the military, which has a history of mounting coups to defend secularism although it has not seized power directly since 1980.

His conservative religious vision for Turkey's future has also alienated many ordinary citizens who accuse him of authoritarianism. Police used heavy force in 2013 to suppress mass protests demanding more freedom.

Erdogan commands the admiration and loyalty of millions of Turks, however, particularly for raising living standards and restoring order to an economy once beset by regular crises.

'NECESSARY MEASURES'

Deputy Prime Minister Mehmet Simsek took to Twitter to try to reassure investors the Turkish government was in full control of the economy before financial markets opened on Monday.

He said it had decided on "all necessary measures" after consulting with the central bank and treasury. He did not specify the measures.

"The macro fundamentals of our country are solid. We are taking all necessary precautions. We are strong with the support of our people and strengthened political stability," he said on Twitter, adding that he planned to hold a conference call with global investors on Sunday.

The central bank said it would provide unlimited liquidity to banks.

For at least eight hours overnight on Friday, violence shook Turkey's two main cities. But the coup attempt crumbled as Erdogan rushed back to Istanbul from a Mediterranean holiday and urged people to take to the streets in support of his government against plotters he accused of trying to kill him.

The violence shocked the nation of almost 80 million, once seen as a model Muslim democracy, where living standards have grown steadily for more than a decade and where the army last used force to stage a successful coup more than 30 years ago.

It also shattered fragile confidence among Turkey's allies about security in the Nato country, a leading member of the US-led coalition against ISIS. Turkey had already been hit by repeated suicide bombings over the past year and is struggling to contain an insurgency by Kurdish separatists.

US President Barack Obama has also urged parties on all sides of the crisis to avoid destabilising Turkey and follow the rule of law.