Angered by the lack of coverage of Turkey's violent crisis in the country's mainstream media, Turks are mobilising via Twitter and Facebook, prompting police to arrest users they accuse of spreading subversion.
Prime Minister Recep Tayyip Erdogan has dismissed Twitter as a "troublemaker" that "terrorises society," ranking it along with the "extremists" he blames for the days of protests against his rule.
But observers say Turks are naturally turning to online social media since even private national broadcasters and newspapers are giving proportionally little airtime and column inches to the protests.
In response the authorities, long accused of repressing journalists, now appear to be targeting ordinary web users as well.
Officers arrested at least 25 people on Wednesday in the western city of Izmir, accusing them of tweeting "misinformation" – news that was in fact reported by local television channels.
Police were still searching for at least a dozen others for tweets the police said contained "misleading and libellous information," Anatolia news agency reported.
"Have they already banned freedom of opinion and I have not heard about it?" tweeted one user, @CRustemov, as the news spread. "What on earth does it mean to get arrested over Twitter!"
Many protesters use Twitter and Facebook on their mobile phones to warn each other where police are firing tear gas or water cannon and to upload pictures of the mass gatherings.
The online platforms have also become a debating chamber among activists venting their views on the government.
"It's not surprising that social media have played a crucial role in popular protests, largely due to the mainstream media's failure to act," said Asli Tunc, a professor at Istanbul's Bilgi University.
"Young Turks are not reading newspapers or watching TV. They are updated by social media, which before were just seen as an entertainment tool to kill time," she told AFP.
"Social media have become a platform of resistance while proving wrong a common perception that the country's youth is highly apolitical."
As clashes broke out across the country last weekend, some prime-time TV stations aired penguin documentaries and cooking shows instead, drawing widespread ridicule.
A video posted on Facebook showed an activist who teased a TV station by calling it to say: "Good evening, there are protests in Taksim Square. I think you don't know about it. I just wanted to let you know. I can be your volunteer reporter."
Crowds demonstrated outside the offices of Turkish media groups, saying they were cowed by the government.
A private TV channel took a popular television game show, "Word Game," off the air without explanation on Wednesday after an episode in which contestants were asked to guess the words "gas mask," "police," and "violence."
The perceived crackdown has alarmed rights groups and highlighted the sensitive role of the popular social media networks in the nationwide protests against Erdogan and his Islamic-rooted government.
"Restrictions on the Internet will only promote rumour and conjecture at a time that the country needs facts and freely expressed views," said Nina Ognianova, regional coordinator for the US-based Committee to Protect Journalists.
"The free exchange of news and information is important at all times, but it is vital at times of unrest as only a well-informed society has the capacity to restore and heal itself."
The authors' rights group PEN said it was "shocked... by the widespread restriction in the media in Turkey in recent days."
Erdogan does not tweet himself, though his supporters post frequent messages in his name.
The thriving social networks have opened a new front in a battle that he has waged against other online platforms in the past.
YouTube was temporarily banned in 2008 after a video was posted on the site showing Greek football fans taunting Turks and making claims about the country's founder, Mustafa Kemal Ataturk.
The site survived as one of the most visited in Turkey, with users resorting to proxy servers to dodge the ban – which was later lifted through a court decision.
"Now is the time to tweet. Prime minister, you are very lucky to be a prime minister of such a wonderful society," tweeted another user, @carolinesirab.
"The revolution will not be televised," wrote another, @ela_suleymangil. "It will be tweeted."