Protesters clashed with police in cities across Turkey on Tuesday after the death of a 15-year-old boy who had been in a coma since he was hit in the head by a tear-gas canister during anti-government demonstrations last summer.
Police unleashed water cannon and tear gas on thousands of demonstrators, another pre-election headache for Prime Minister Tayyip Erdogan as he battles a corruption scandal that has become one of the biggest challenges of his decade in power.
Istanbul and Ankara have both seen protests in recent weeks against what demonstrators regard as Erdogan's authoritarian reaction to the graft affair, which has included new laws tightening Internet controls and handing government greater influence over the appointment of judges and prosecutors.
Turkish President Abdullah Gul approved a law in February which allows the telecommunications authority to block websites without a court authorization. It also requires Internet providers to keep records of users' activities for two years and make them available to authorities.
The move is seen by critics of Erdogan as an authoritarian response to a corruption inquiry shaking his governmentand a bid to stop leaks from circulating online.
The European Union had called the legislation "a step back" for media freedom.
The government says the laws will further democracy by protecting individuals' privacy on the Internet.
Berkin Elvan, then 14, got caught up in street battles in Istanbul between police and protesters on June 16 while going to buy bread for his family. He slipped into a coma and became a rallying point for government opponents, who held regular vigils at the hospital where he lay in intensive care.
On Tuesday evening, police fired water cannon and tear gas in Ankara's central Kizilay square to scatter several thousand protesters who chanted: "Government of Erdogan, government of corruption, resign resign." The police pursued the protesters into sidestreets where small clashes continued.
There was similar police intervention against thousands of protesters on both the European and Asian sides of Istanbul, among dozens of places across Turkey where posts on social media had called for protests on Tuesday evening.
In the Mediterranean city of Mersin, two women were injured when they were struck by a water cannon vehicle, one of them suffering a head wound, the Dogan news agency said. Four police were also reported injured in the clashes there.
Police detained 20 people as they skirmished with protesters trying to march to the offices of Erdogan's AK Party in the Black Sea city of Samsun, Dogan reported.
In the southern city of Adana, protesters threw stones and aimed fireworks at police lines as water cannon vehicles advanced against them, spraying water. Large numbers also protested in the western cities of Izmir and Eskisehir in the most extensive protests since last summer's unrest.
Residents in some Istanbul districts banged pots and pans with spoons from the windows of their apartment blocks, reviving a form of protest popular during the summer.
Crowds chanted "murderer Erdogan" and "the murderer state will be brought to account" as mourners carried Elvan's coffin, wrapped in red cloth and strewn with red carnations, to a "cemevi," an Alevi place of worship, in central Istanbul.
Alevis are a religious minority in mainly Sunni Muslim Turkey. They espouse a liberal version of Islam and have often been at odds with Erdogan's Islamist-rooted government.
Among the crowd of as many as 1,000 people, some waved plain red flags, while shopkeepers in the Okmeydani district pulled down their shutters as a mark of respect. Elvan's mother, flanked by a group of women, stood crying at an open window.
"We have come here because of the murderer police. They will be held to account. Berkin Elvan's blood will not be left on the ground," said Ahmet Ekinci, one of those in the crowd.