Riot police fire a water cannon to disperse the protesters as a protester pushes on their truck. Murad Sezer/Reuters

Protesters are hit by water cannon during the clashes with riot police over Elvan. Gurcan Ozturk/AFP/Getty Images

The night before the funeral, the announcement of Elvan’s death triggered protests in downtown Istanbul, leading protesters to clash with police. Here, the protesters throw fireworks toward the police. Erdem Sahin/EPA

People carry the coffin of Berkin Elvan, 15, who died after 296 days in a coma, during a ceremony Wednesday in Istanbul. Elvan had been in a coma since June 2013 after being injured when a gas canister struck him during the police crackdown on protesters at Gezi Park. Sedat Suna/EPA

Tens of thousands of mourners chanting anti-government slogans marched through central Istanbul on Wednesday for the funeral of a teenager wounded in street protests last summer whose death has sparked renewed unrest across Turkey.

Riot police fired water cannons and tear gas at protests in several cities after Berkin Elvan's death on Tuesday, nine months after he slipped into a coma, adding to pre-election woes for Prime Minister Recep Tayyip Erdogan as he battles a corruption scandal that has become one of the biggest challenges of his decade in power.

Crowds chanting "Tayyip! Killer!" and "Everywhere is Berkin, everywhere is resistance" held up photos of Elvan outside a cemevi, an Alevi place of worship, in Istanbul's working-class Okmeydani district, from where his coffin, draped in red and covered in flowers, was carried through the streets for burial.

Alevis are a religious minority in mainly Sunni Muslim Turkey who espouse a liberal version of Islam and have often been at odds with Erdogan's Islamist-rooted government.

Police in the capital, Ankara, fired tear gas to disperse several thousand protesters in the central Kizilay square, and there were also clashes in the poor Alevi neighborhood of Tuzlucayir across the city.

Erdogan, on the campaign trail ahead of municipal elections on March 30, addressed a rally in the southeastern city of Siirt but failed to mention the teenager's death in a speech of almost an hour.

Referring to last summer's protests, he accused a coalition of "anarchists, terrorists and vandals" as well as the opposition and followers of an influential U.S.-based Islamic cleric of stoking trouble on the streets to undermine him.

"Don't worry, we will hold them to account. You will hold them to account at the ballot box on March 30," he thundered.

Anger at the perceived growing authoritarianism of Erdogan motivated many attending the funeral procession in Istanbul.

"The lack of compassion, the polarizing attitude of the prime minister and the fact that he behaves like an autocrat is what brought us here," said Emre, 32, marching with his father-in-law.

The funeral ceremony was broadcast live on major television news channels, some of which were criticized for their scant coverage of last June's unrest.

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 became a rallying point for government opponents, who held vigils at the Istanbul hospital where he lay in intensive care from a head trauma believed to have been caused by a police tear gas canister.

His death has sparked the most extensive street protests since last June, with skirmishes on Tuesday in cities including Mersin on the Mediterranean coast, Samsun on the Black Sea and the southern city of Adana, as well as Istanbul and Ankara.

Erdogan has yet to comment on Elvan's death. He dismissed last summer's protesters as riffraff, and has cast both those weeks of unrest and the corruption scandal that erupted in December as part of an orchestrated campaign to undermine him.

The uncertainty in the run-up to elections has unnerved Turkish investors, with the lira languishing at its weakest in five weeks, but has shown little sign so far of unseating the prime minister, fiercely popular in the conservative Anatolian heartlands for delivering a decade of rising prosperity.

"The recent barrage of corruption allegations ... appears to have had little impact on Erdogan's electoral popularity, merely deepening the political divides in an already highly polarized society," said Wolfango Piccoli, managing director of the research firm Teneo Intelligence. "[But] the death of a child on his way to buy bread for his family is something that cuts across political divides and will have particular resonance amongst the urban and rural poor who form Erdogan's core support base."

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.

But opinion polls suggest that while support for his AK Party may have slipped, it remains comfortably ahead of rivals.

Protesters stood by fires at barricades blocking roads around the Okmeydani neighborhood. Signs on shop windows said stores would remain shut for two days, while traders sold black and white flags bearing Berkin Elvan's face.

Two labor unions called a one-day strike and encouraged members to attend the funeral, while professors at some universities announced they were canceling classes.

In the eastern province of Tunceli, which has an Alevi majority, around 1,000 schoolchildren marched across town and staged a sit-in in front of the offices of the ruling AK Party.

The boy's father, Sami Elvan, received mourners in front of the cemevi. Berkin's mother, Gulsum Elvan, embraced the mother of a man who died during last summer's protests, Ethem Sarisuluk.

"This is just the beginning. Continue the struggle," the crowd chanted.

Reuters