At least 6,000 people have been arrested in connection with the failed attempt to bring down Turkey's government, reports say.

Senior military commanders, rank-and-file soldiers and thousands of judges are among those rounded up in a sweeping crackdown.

A few groups of plotters are still holding out against in Istanbul, according to a senior official speaking to Reuters.

However, he said that the government was back in control of the country and the remaining leaders of the coup were expected to be arrested shortly.

Meanwhile, thousands of supporters gathered in Taksim Square in Istanbul singing songs and waving flags, with similar scenes in the capital Ankara and other cities.

"We are here for democracy, so the country lasts," retired soldier Nusret Tuzak said at the Ankara gathering.

At least 161 civilians and troops loyal to the government were killed as a small group declared martial law and a curfew, occupying key sites and blocking bridges across the Bosphorus.

Another 100 coup plotters died as the attempt to topple President Recep Tayyip Erdogan was crushed, according the government.

But one Turkish official told Reuters the death toll stood at 265 - including 161 civilians and police and 104 coup supporters.

There is also speculation the death penalty could be reintroduced.

President Erdogan has asked the United States to extradite Fethullah Gulen, a moderate cleric exiled in Pennsylvania who is accused of masterminding the plot.

Mr Gulen has denied any involvement and says he condemns the attempted coup "in the strongest terms".

Prime Minister Binali Yildirim said the perpetrators of the failed coup "will receive every punishment they deserve" - but the US urged caution.

The White House said Barack Obama had "registered the vital need for all parties in Turkey to act within the rule of law and to avoid actions that would lead to further violence or instability".

Eight soldiers who fled in a military helicopter to Greece will hear their fate on Sunday following Turkey's call to "extradite the eight traitors as soon as possible".

Defence minister Fikri Isik said the Turkish government is now in full control of all areas in the country, but stressed that "at any time there could be new tests and new attempts" to impose martial law.

Turkey's four main political parties held an extraordinary parliamentary meeting on Saturday, and issued a joint statement strongly condemning the coup.

Meanwhile, flights into Istanbul's international airport have resumed after being halted for nearly 24 hours.