Tens of thousands of Turks on Sunday flocked to a rally in Istanbul organized by the main opposition but joined by the ruling party as well to say "no" to the failed coup attempt a week ago.

The ruling Justice and Development Party (AKP) decided to be present for the rally held by the secular Republican People's Party (CHP) in Taksim Square at the heart of Istanbul, on the grounds that it is no longer the issue for one political party to denounce the coup attempt.

AKP's representatives and supporters joined the massive rally, which also drew unions, leftist and LGTBI (lesbian, gay, bisexual, transgender and intersex) groups.

Many more Turks poured into the square by responding to calls on social media for "shoulder to shoulder" acts.

"Neither autocracy nor coup, democratic Turkey!" read a red-and-white giant banner hanging over the square.

In his speech, CHP leader Kemal Kilicdaroglu called for "unity and solidarity" against all kinds of coup attempts targeting the parliamentarian system.

"We strongly condemn and curse all the perpetrators of the coup attempt and its internal and foreign supporters," he said.

Semiha Karasoy, a woman holding on her chest a picture of Mustafa Kemal Ataturk, the founder of modern and secular Turkey, said she was here "for a democratic and secular Turkey."

Hulya Kocak, another woman, said she is hopeful for the future and was here to honor the republic and Ataturk.

Extreme security measures were taken across the area by thousands of police officers, with bomb squad teams having scanned the square with trained dogs hours before the start of the rally and people passing through several security check points.

Since July 15, Turks have been flocking to squares every evening to "protect democracy," as being called for by Turkish President Recep Tayyip Erdogan who had warned of the threat of a second coup attempt.

On Wednesday night, Erdogan declared a three-month state of emergency nationwide.

Turkish authorities have accused U.S.-based cleric Fethullah Gulen of orchestrating the coup attempt in coordination with a faction within the military and demanded his extradition.

All the political parties in Turkey have expressed "unity and solidarity" against the overthrow bid, which Erdogan said has left 246 dead and 2,185 others injured.

A massive crackdown has resulted in 11,160 suspects detained, mostly from the military, police and judiciary, according to the president.