Turkish police have used tear gas and water cannon against protesters occupying Gezi Park in central Istanbul.
Scores of people have suffered injuries, several of them when a wall collapsed during a police chase.
Demonstrators had been camping since Monday in Gezi Park, angry at plans to develop it as part of a revamp of Taksim Square, in which it is situated.
Many protesters also expressed discontent with the government of PM Recep Tayyip Erdogan.
Recep Tayyip Erdogan has been in power since 2002 and some in Turkey feel that his government is becoming increasingly authoritarian.
Last week, Turkey’s parliament approved legislation restricting the sale and consumption of alcoholic drinks.
The regulations would prohibit retail sales between 22:00 and 06:00, ban all alcohol advertising and promotion, and stop new shops and bars from opening within 100 m (330 ft) of schools and mosques.
Recep Tayyip Erdogan said he wanted to stop young Turks from “wandering about in a state of inebriation” and was not trying to impose Islamic values.
The prime minister’s Justice and Development (AK) Party has its roots in political Islam, but he says he is committed to Turkey’s state secularism.
Opponents to Recep Tayyip Erdogan’s plans to re-develop Gezi Park say it is one of the few green areas left in central Istanbul.
One banner at Friday’s protest included a cartoon of Recep Tayyip Erdogan dressed as an Ottoman sultan with the slogan: “The people will not bow down to you.”
“We do not have a government, we have Tayyip Erdogan,” political scientist and protester Koray Caliskan told the Reuters news agency.
“They are not listening to us,” he added.
“This is the beginning of a summer of discontent.”
Hurriyet Daily News reported that seven of those wounded in the clashes with police had serious injuries, including a broken leg and head injuries.
A journalist was hit in the head with a tear-gas canister and Hurriyet‘s own photographer was injured, it added.
Amnesty International condemned the use of what it called “excessive force” against “peaceful protesters”.