Police in Istanbul fired water cannons and tear gas at thousands of protesters in Taksim Square.
Protesters converged on the site Saturday, blatantly disregarding warnings to stay away. Organizers said they intended to march into the adjacent park that has been cordoned off by police.
The area has been the site of anti-government protests and clashes with police since late May, when police forcefully broke up a demonstration against a government plan to develop the park for commercial use. At least three civilians and one policeman have been killed, and many more injured, during the past month.
Protesters are angry at Prime Minister Recep Tayyip Erdogan, who has threatened to use the army to disperse demonstrations, if necessary.