ISTANBUL (AFP) - Many thousands of flag-waving Turks massed Sunday for the first cross-party rally to condemn the coup attempt against President Recep Tayyip Erdogan, amid an ongoing purge of suspected state enemies.
Istanbul's Taksim square was transformed into a sea of red national flags in what was dubbed a "democracy festival".
But in stark contrast to the celebratory and patriotic mood in Istanbul, human rights group Amnesty International in London claimed it had "credible evidence" of the beating and torture of detainees.
The official number of those in custody since the July 15 putsch has surged above 13,000 soldiers, police, justice officials and civilians in a wave of arrests that has alarmed NATO allies and European leaders.
Despite the high tensions since the coup attempt, the mood in Istanbul was celebratory and strongly patriotic, with security tight following a series of recent attacks by Islamic State extremists and Kurdish militants.
"We defend the republic and democracy" read one sign in the vast and jubilant crowd, while others declared "Sovereignty belongs to the people alone" and "No to the coup, yes to democracy!"
The mass event was called by the biggest opposition group, the secular and centre-left Republican People's Party (CHP), many of whose members carried pictures of modern Turkey's founding father Mustafa Kemal Ataturk.
To signal patriotic unity and make the rally a cross-party event, it was joined by Erdogan's Islamic-conservative AKP, whose followers have rallied in support of the president every night since the failed putsch.
CHP leader Kemal Kilicdaroglu in a speech to the rally said that amid the turmoil, "the parliament stood proudly, Turkey stood proudly, MPs stood proudly, people in this square have stood proudly, and democracy won!"
Prime Minister Binali Yildirim tweeted that "this country's Turks, Kurds, Alevis" and supporters of the major opposition parties "united together and gave the lesson needed to the putschists".
In London, Amnesty made serious claims about methods the government has allegedly used to rid the state of suspected conspirators.
Amnesty claimed it had "credible evidence" that some detainees were being "subjected to beatings and torture, including rape, in official and unofficial detention centres in the country".
Amnesty said it had received reports that detainees were being denied food, water and medical treatment and being held in "stress positions" for up to 48 hours.
It said its report was based on interviews conducted with lawyers, doctors and one person on duty in a detention facility.
"Turkey is understandably concerned with public security at the moment, but no circumstances can ever justify torture and other ill-treatment or arbitrary detention," said Amnesty's Europe director John Dalhuisen.
He urged the Turkish authorities to stop "these abhorrent practices" and allow international monitors into detention centres.
In Ankara, a senior official denied Amnesty's claims, saying: "The idea that Turkey, a country seeking European Union membership, would not respect the law is absurd".
"We categorically deny the allegations and encourage advocacy groups to provide an unbiased account of the legal steps that are being taken against people who murdered nearly 250 civilians in cold blood." Turkey has undergone a seismic shift since the night of violence when renegade soldiers sought to topple Erdogan but were stopped by crowds of civilians and loyalist security forces.
In the latest reaction, Yildirim said Turkey would disband Erdogan's 2,500-strong Presidential Guard, saying there was "no need" for the elite regiment.
Almost 300 of its officers had already been detained after some guards forced TV news presenters to read statements declaring martial law during the abortive coup attempt.
Under new police powers decreed as part of a three-month state of emergency, those detained can be held without charge for 30 days.
Erdogan's government has sacked thousands of teachers, professors and civil servants and closed schools and universities.
Also targeted in the sweep was an alleged senior aide to US-based cleric Fethullah Gulen - the reclusive spiritual leader whom Turkey accuses of having orchestrated the plot to overthrow Erdogan.
Security forces detained Halis Hanci in the Black Sea province of Trabzon, a senior official said, describing him as a "right-hand man" to 75-year-old Gulen and responsible for handling finances for him.
The preacher - who lives in a secluded compound in rural Pennsylvania and whose foundation runs a global network of schools, charities and media interests - has strongly denied the accusations against him.
The Armed Forces Chief of General Staff, General Hulusi Akar, described the renegade soldiers as "the vile, uniformed traitors (who) damaged our country, people and our armed forces in a major way. They will face serious punishment".