Thousands of people took to the streets of Istanbul overnight on Sunday, erecting barricades and starting bonfires, after riot police used teargas and water cannons to clear the protest camp at the centre of Turkey's anti-government unrest.

In a night of chaotic violence large areas of the city around the now symbolic area of Gezi Park were engulfed in plumes of tear gas, while protesters opposed to the government of Turkey's prime minister Recep Tayyip Erdogan attempted to push back to the city's central Taksim Square.

The continuing protest through the night, and calls for fresh demonstrations at 4pm on Sunday suggested that despite the clearing of the encampment in the park, Turkey's crisis was far from over.

In the immediate aftermath of the police operation trade unionists called for a national strike on Monday.

Underlining how deeply personal the issue has become for Erdogan, a spokesman for his AKP party blamed the protesters for allegedly reneging on a deal with Erdogan thrashed out two nights before.

"A country's prime minister meets you for 10 hours, you reach an agreement then say something else behind his back," Huseyin Çelik said in a TV interview defending the assault. "Wouldn't you feel cheated?" he told the private broadcaster Habertürk.

The lightning evening assault on the park and nearby square followed a warning from Erdogan that protesters should quit Gezi Park or be removed by security forces ahead of a rally of his supporters in Istanbul on Sunday.

Protesters took to the streets in several neighbourhoods across Istanbul following the raid on Gezi Park, ripping up metal fences, paving stones and advertising hoardings to build barricades and lighting bonfires of rubbish in the streets.

During the raid police fired tear gas against the volunteer doctors manning a clinic in the park who have been working anonymously for fear of losing their jobs.

In the early hours of the morning groups of demonstrators blocked a main highway to Ataturk airport on the western edge of the city, while to the east, police fired tear gas to block protesters attempting to cross the main bridge crossing the Bosphorus waterway towards Taksim.

Thousands more rallied in the working-class Gazi neighbourhood, which saw heavy clashes with police in the 1990s, while protesters also gathered in Ankara around the central Kugulu Park, including opposition MPs who sat in the streets in an effort to prevent the police firing teargas.

A demonstrator is surrounded by riot police in Istanbul. Photograph: Reuters

In the last 18 days Gezi Park, with its tented encampment occupied by an umbrella of groups including football fans, nationalists, environmental campaigners, Kurds and young Turks from many walks of lives, had come to represent a new spirit of social resistance to what many fear is the increasingly authoritarian style of Erdogan and his moderate Islamist AKP.

Erdogan had delivered his warning at a rally of tens of thousands of AKP supporters in Ankara, the national capital, promising that Taksim Square would be cleared by Sunday in time for a second rally there.

"We have our Istanbul rally tomorrow," Erdogan warned. "I say it clearly: Taksim Square must be evacuated, otherwise this country's security forces know how to evacuate it."

Barely two hours later white-helmeted riot police assaulted Gezi Park shortly after a concert attended by protesters and tourists drew to a close. Protesters had vowed earlier to continue with their occupation, although they had promised to remove barricades and reduce the number of tents in the park. Police had given 15 minutes' notice to clear the park and the adjoining Taksim Square before storming the protest camp.

Police warned protesters: "This is an illegal act, this is our last warning to you – evacuate."

The speed of the move to seize the square and park caught protesters by surprise. They were quickly scattered by teargas canisters and rubber bullets. Within 20 minutes a bulldozer had moved in to demolish structures and tents that had been used by the anti-government movement. A little later police and municipal workers could be seen tearing down fences around the park and removing tents.

Children and tourists were among those caught up in the assault, amid reports of many injuries. But despite quickly taking control of the park, running battles between police and thousands of protesters, driven back into the warren of side streets beside the square, carried on for hours afterwards.

At one stage a bearded middle-aged man draped himself over the plough of one of the water cannons to try to prevent it moving forwards before he was beaten back by batons and gas. Protesters sought refuge in hotels and cafes, including hundreds in the Divan hotel, which was stormed by police.

Later police stormed the hotel beating protesters, while a later assault left the lobby of the luxury hotel thick with gas. The Guardian saw two elderly women who had passed out being carried out on stretchers to an ambulance.

Earlier riot police had stormed into the lobby, beating those inside.

Many had been expecting a final move to clear the park after Erdogan's speech. But none had anticipated the action would begin so quickly. Tayfun Kahraman, a member of Taksim Solidarity, an umbrella group of protest movements, said an unknown number of people in the park had been injured, some by rubber bullets.

A leading public-sector union alliance, KESK, said it would call a national strike for Monday.

Police cordon off Taksim Square on Sunday morning. Photograph: Vadim Ghirda/AP

NUT executive member Martin Powell-Davies was part of a British trade union delegation that had approached the fringes of the square as police moved in. He said: "There was a concert by a well-known musician with hundreds of people and families in a festival atmosphere in the square and then suddenly from all sides the police came with water cannons and teargas."

He struggled to speak as he choked on teargas and protesters regrouped to chant anti-government slogans. He said: "There are hundreds of Istanbul residents who have come out on to the streets to show their opposition. They are banging the shutters in protest at the sides of the streets."

The assault followed Erdogan's defiant message delivered in a suburb of Ankara, depicting those on the streets as "traitors playing a game", "looters" or part of a conspiracy against the government.

"Anyone who wants to hear the national will, should come and listen to [Ankara]," Erdogan said. "We are not like those who took molotov cocktails, or honked their car horns. I tell you it's a crime to violate order." He insisted, once again, that he and the AKP had a clear mandate to govern.

Oguz Kaan Salici, Istanbul president of the main opposition People's Republican Party, said: "The police brutality aims at clearing the streets of Istanbul to make way for Erdogan's meeting tomorrow. Yet it will backfire. People feel betrayed."