Turkey on Tuesday hit Twitter, Pinterest and Periscope with advertising bans after they failed to follow Facebook and appoint a local representative to take down contentious posts under a new media law.
Freedom of speech defenders warn the law is part of Turkish President Recep Tayyip Erdogan's attempt to control social media and stop any dissent against his government.
The social media legislation passed last year meant networks with over a million users had to appoint an envoy to handle court orders to remove offending content within 48 hours.
The bans on the three platforms came into force Tuesday while companies who advertise with them will also be fined, Turkey's deputy infrastructure minister Omer Fatih Sayan tweeted.
Ankara is "determined to do whatever is necessary to protect our people's data, privacy and rights," Sayan added.
"We will never allow digital fascism and rule-breaking to dominate in Turkey," he said.
If the networks continue to ignore the law, Turkey will cut their bandwith by 50 percent in April then 90 percent by May, thus rendering them effectively inaccessible.
Some platforms that failed to comply by the first deadline last November, including Facebook and Twitter, were hit millions of dollars in fines.
Facebook said Monday it will appoint a local envoy but recognised "how important it is for our platform to be a place where users can exercise their freedom of expression".
It joins YouTube, TikTok and Dailymotion in compliance, drawing anger from activists. Facebook's Russian equivalent VK opened a local office in November.
Milena Buyum, Amnesty International's Turkey campaigner, said Monday that "Facebook's decision leaves them - and Google, Youtube and others - in serious danger of becoming an instrument of state censorship".
Research shows that as Erdogan's grip on mainstream media tightened, especially since he survived a failed coup in 2016, younger people have sought information online, especially on social media.
Although Turkey named Periscope in the decisions, Twitter last month said its mobile app for live streaming video will shut down by March as usage declined.
The "cyber world... has become a threat to humanity", Erdogan warned last week, promising commitment to a "cyber homeland" as part of Turkey's defence.
"Those who control data can establish their digital dictatorships by disregarding democracy, the law, rights and freedoms," the president added.