A Turkish court blocked access to numerous sites including Twitter and YouTube on Monday, over their hosting of images of an Istanbul prosecutor held at gunpoint by militants last week.
An Istanbul court issued the ruling blocking Twitter and YouTube, as well as 166 other sites that had distributed the photograph, a report in The New York Times said. It also blocked the pages of several newspapers in Turkey that had printed the photo.
Turkey's Prime Minister, Ahmet Davutoglu, called outlets that had circulated the image "tools of terrorist propaganda," the Times reported.
Twitter said Monday that it was "working to restore access for our users as soon as possible." A company spokesman declined to comment further.
YouTube did not immediately respond to a request for comment.
Turkish authorities also issued a court order to Facebook to restrict access to the photo, threatening to block its service if it did not comply. Facebook has complied but will be appealing the order, a company spokesman said.
Twitter, YouTube and Facebook ban content containing direct threats of violence against others. But Facebook has also grappled with restricting some types of violent content when the content might also help to raise public awareness around a sensitive issue.
Turkey has blocked social media sites like Twitter and Facebook before. Earlier this year the country blocked some content on Facebook after authorities said it was insulting to the Prophet Muhammad.