Hundreds of Turkish police in riot gear breached barricades to force their way into Istanbul's central Taksim Square and fired tear gas at protesters in an attempt to take back control of the makeshift camp, as the prime minister warned "no one will get away with it".
Speaking in Ankara as the police operation unfolded in Istanbul, Prime Minister Recep Tayyip Erdogan urged demonstrators to leave the square and insisted the protests were part of a conspiracy against the government.
"To those who ... are at Taksim and elsewhere taking part in the demonstrations with sincere feelings: I call on you to leave those places and to end these incidents and I send you my love. But for those who want to continue with the incidents I say: 'It's over.' As of now we have no tolerance for them," Mr Erdogan said.
"Not only will we end the actions, we will be at the necks of the provocateurs and terrorists and no one will get away with it," he added.
"I want everyone there to see the big picture, to understand the game that is being played and I especially invite them to evacuate (Taksim and Gezi Park). I expect that of them as their prime minister.
"A comprehensive attack against Turkey has been carried out," Mr Erdogan told parliamentary group meeting of his AK Party.
He added: "The increase in interest rates, the fall in the stock markets, the deterioration in the investment environment, the intimidation of investors - the efforts to distort Turkey's image have been put in place as a systematic project."
Police fired rubber bullets at protesters in Taksim Square, prompting many to flee the square into adjoining Gezi Park, where some have been camping. There were running battles at one edge of the square between police and some groups of protesters, who responded by throwing fireworks, firebombs and stones at a police water cannon.
Police made frequent announcements through loudspeakers, asking the group to stop attacking police, before then firing the tear gas. A water cannon was also used to douse another police vehicle that was set alight by a firebomb.
Officers in riot gear, backed by armoured vehicles and carrying shields gathered around the square before moving past barricades erected by protesters. They removed protesters' banners which had been hung from a building overlooking the square. Activists replaced a large Turkish flag and a banner with a picture of Mustafa Kemal Ataturk, the founder of the secular republic 89 years ago after the collapse of the Ottoman Empire.
The latest police clampdown, on the 12th day of nationwide protests, comes after Mr Erdogan agreed to meet the protest organisers on Wednesday. Mr Erdogan is trying to reign in mass protests that have spread across Turkey – a large-scale show of anger against what many view as his government’s authoritarian policies. The protests gained momentum after police used tear gas against a peaceful sit-in in Istanbul’s Gezi Park on 31 May, objecting to the demolition of the park for a commercial development.
The Turkish Human Rights Foundation raised the number of deaths in more than a week of protests to four.
The protests grew into wider demonstrations against what many see as an authoritarian style of governing and Mr Erdogan's perceived attempts to impose a religious and conservative lifestyle in a country which has secular laws. Mr Erdogan, a devout Muslim, says he is committed to Turkey's secular laws and denies charges of autocracy.
He has escalated tensions by vowing to press ahead with the Taksim redevelopment plans, dismissing the protesters as fringe extremists and the protests as undemocratic plots to topple his government, which was elected with 50 per cent support.
He called major pro-government rallies in Ankara and Istanbul this weekend to show that he too can get large numbers of his supporters out on the street.
Huseyin Avni Mutlu, governor for Istanbul, said in a message issued on his Twitter account that the police operation was to dismount the banners hung on the building and at a monument on the square. He said people occupying the park at the square would not be touched.
Hundreds of protesters remain inside Gezi park, some still sleeping in tents, some eating breakfast handed out by volunteers. Those affected by tear gas at Taksim were helped to the medical station.
One protester said he joined the protest in Gezi Park because his cousin was beaten by police during the initial clampdown that sparked the wider protests.
"I'm here because I'm trying to defend my human rights," said the protester, who identified himself as Kenan Agac. "I'm not against police but his morning they came and threw tear gas."
"If they had warned us, this wouldn't have happened. This was not necessary."
The Turkish government announced after a Cabinet meeting that Mr Erdogan would meet some of the peaceful Gezi Park protesters but authorities would not allow "illegal" demonstrations to continue.
Before the police action, the protests appeared to be on the wane, with the smallest number of demonstrators in the past 12 days gathering in Taksim last night. The protesters occupying Gezi Park had remained.
Smaller protests occurred in Ankara, with about 5,000 people demonstrating. Police there have used water cannon and tear gas to break up demonstrations almost every night.