Riot police have moved into Taksim Square and Gezi Park. Tear gas and water cannons were fired to force the thousands of demonstrators out of the two areas in central Istanbul.
The show of force came just hours after Prime Minister Recep Tayyip Erdogan fired a warning to the protesters that the police were ready to intervene.
Tens of thousands have been protesting in the two sites for over a week.
“I say it clearly: Taksim Square must be evacuated, otherwise this country’s security forces know how to evacuate it,” Erdogan had told his supporters at a rally in the capital Ankara.