Battling a corruption scandal, ErdoÄŸan's Justice and Development Party (AK Party) has pushed through laws tightening government control over the Internet and courts this month, and has proposed a bill envisaging broader powers for the national intelligence agency.
Officers backed by water cannon cleared demonstrators from the main İstiklal shopping street, some chanting "Everywhere Taksim, Everywhere Resistance", a reference to weeks of anti-government protests last summer on the nearby Taksim Square.
"(Prime Minister) Tayyip ErdoÄŸan, don't pull the Internet plug," read one banner among the crowds.
"We are here because we are sick and tired of Tayyip's angry scolding and AK Party laws trying to limit every freedom we have," said Sinem Gül, a 26-year-old architect.
Tear gas spread into shops and restaurants as police chased demonstrators into side streets, in the second such protest in recent weeks.
ErdoÄŸan's critics see the new laws as an authoritarian backlash against the corruption inquiry shaking his government, which his supporters say is a plot against him by powerful US-based cleric Fethullah Gülen.
Social media and video-sharing sites have been awash with leaked recordings presented as evidence of government wrongdoing since the corruption scandal erupted in December.
The government says the laws - including the Internet bill which allows web pages to be blocked within hours - protect privacy and defend democracy in the face of a bid by Gülen to manipulate state institutions, a charge the cleric denies.
The graft scandal poses one of the greatest threats to ErdoÄŸan's 11-year-old rule and his response, including dismissing or reassigning thousands of police officers and hundreds of prosecutors and judges, has betrayed what critics say are increasingly authoritarian tendencies.
Gülen has denied orchestrating the scandal and his supporters have said they are the victims of a witch-hunt.
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