Istanbul came to a standstill on Sunday as an army of riot police and gendarmerie cordoned off streets and use teargas on protesters in the centre of the city while the prime minister, Recep Tayyip Erdogan, staged a rally before hundreds of thousands of supporters at the waterfront.

Some 24 hours after using brute force to clear the focal point of the demonstrations against the government and bulldozing Gezi Park in Taksim Square, where a varied crew of protest groups had been camped out since the beginning of the month, Erdogan ditched all efforts at conciliation at a rally of his Justice and Development party (AKP).

"Taksim is not Turkey," Erdogan declared, in a reference to the city centre square ringed off by riot police on Sunday evening as thousands of demonstrators sought to converge there.

Protest organisers had called for a million-strong demonstration at Taksim Square, but the entire area was cordoned off, making access impossible. Stretches of the motorways encircling Istanbul were also closed by police to try to prevent protesters getting to the city centre.

The opposite conditions applied to government supporters making their way en masse to hear the prime minister. The Istanbul municipality and the AKP laid on buses and other transport to help boost the numbers attending.

Erdogan inveighed against the international media, blaming the BBC and CNN for distorting the drama of the past three weeks in what he repeatedly alleged was an international plot to divide and diminish Turkey.

"You will make your voice heard so anyone conspiring against Turkey will shiver," he told the crowd. "Turkey is not a country that international media can play games on."

He added that the Turkish nation "is not the one banging pots at nights", in reference to what has become a soundtrack to the protests: middle-aged people coming on to their apartment balconies nightly to hammer on kitchen utensils.

The same din was heard across several central Istanbul neighbourhoods on Sunday evening.

While Erdogan addressed the massive crowds in bright sunshine, much of the city was sullen and tense. In several districts middle-aged women kept up a steady racket by beating pots and pans from their balconies as riot police lounged around, sitting on pavement verges.

The police raids, which started on Saturday afternoon and quickly cleared and occupied Gezi Park, included acts of startling brutality that outraged normally apolitical Istanbul citizens, as well as human rights monitors.

Teargas was fired into impromptu medical clinics housed in tents. A luxury hotel on Taksim Square being used as an emergency refuge for victims and for the wounded was repeatedly invaded by the police and teargas fired into the enclosed spaces.

"It was horrible in there," said Mehmet Polat, 32. "They shot teargas inside the hotel several times, the gas rose up to the sixth floor of the hotel, everything was filled with white smoke."

Another young man next to him nodded. "People were shoving each other, panicking, but the police kept attacking us." Both were not giving up. "Our demands are very clear," Polat said. "And until they are met, we are not going anywhere."

But on Sunday Turkey's minister for European affairs, Egemen Bagis, said any civilians entering Taksim Square would be viewed as terrorists.

Gezi Park was completely cleared of the gaudy paraphernalia of pluralist protest that had been its hallmark.

Stands, tents and banners were all gone. The central park fountain, decorated with flags of a wide array of political factions on Saturday morning, was adorned with one single Turkish flag the following morning.

Istanbul's governor, Huseyin Avni Mutlu, said no one would be allowed to return to the park to protest.

Erdogan's confrontational style, his divisive rhetoric and the extreme force used by the police on victims including young children, with one pregnant woman losing her baby on Saturday evening, have tarnished his credentials internationally as a reformist Muslim leader.

But the strong-arm tactics do not appear to have closed down the protests and have sown dismay among many non-political Turks.

One policeman guarding the entrance to Gezi Park said he was not happy with the way things were going: "The government is working against the people, and they are using the police to do it. They are handling it very badly. I hate doing this."

At a mobile clinic on the square, one medic said: "They promised us that they would not attack our field hospital, but they did anyway, firing six rounds of teargas directly into our tent.

"This is against all human rights agreements. A serious crime. Not even in war should medical facilities be attacked. But we will remain here and continue our work."

The Turkish health ministry has been issuing threats in recent days, warning that all health professionals treating protesters during the Gezi Park protests would be prosecuted.

Amnesty International said about 100 people had been detained and were being held incommunicado.

"The authorities are denying due process to those they have detained. The police must release them immediately or disclose their location and allow access to family members and lawyers," said Andrew Gardner, Turkey researcher at Amnesty International.