Twitter became inaccessible on major Turkish mobile providers on Wednesday as online criticism mounted of the government's response to this week's deadly earthquake.
AFP reporters were unable to access the social media network in Turkey. It was still accessible using VPN services that disguise a user's location.
The netblocks.org social media monitor said Twitter was being restricted "on multiple internet providers in Turkey".
"Turkey has an extensive history of social media restrictions during national emergencies and safety incidents," the monitor added.
Turkish police have detained more than a dozen people since Monday's earthquake over social media posts that criticized how President Recep Tayyip Erdogan's government has been dealing with the disaster.
Monday's 7.8-magnitude tremor and its aftershocks killed at least 11,200 people in southeastern Turkey and parts of Syria.
Turkish social media have been filled with posts by people complaining about a lack of search and rescue efforts in their provinces.
The Twitter outage came as Erdogan toured two of the hardest-hit Turkish provinces.
Turkish officials released no immediate statements about the service disruption.
But they had issued repeated warnings about spreading misinformation in advance of a crucial May 14 election in which Erdogan will try to extend his two-decade rule.