Turkish police have used water cannon and tear gas against anti-government rallies in several cities, with protesters using social media to report numerous injuries.
Saturday's clashes occurred in Istanbul, Ankara and Hatay. Police fired rubber bullets on demonstrators in Istanbul.
There were internet calls for medical help for about 100 people at Kugulupark in Ankara.
Police used force to disperse about 1,000 demonstrators who tried to march onto Istanbul's Taksim Square in Gezi Park, the focus of street protests for weeks.
Environmentalists opposed to plans to build a shopping mall and hotel in the park staged protests in late May, which widened into mass demonstrations against what they alleged were Prime Minister Recep Tayyip Erdogan's attempts to institute conservative Islamic rule.
Clouds of tear gas wafted through a busy commercial and night-life district around Taksim Square late on Saturday.
Turkish broadcaster Ulus TV posted photos on Facebook showing apparently civilian men, allegedly government supporters, wielding wooden clubs against demonstrators and journalists.
The latest demonstrations were sparked after the brief arrests and prosecution of prominent anti-Erdogan activists, who alleged police abuse.