Turkish authorities are reported to have blocked websites used to spread pictures of a prosecutor who was recently killed by militants. It is not the first time that Ankara has blocked such websites.
Turkish Internet users first reported early on Monday being unable to access the social media websites Twitter, Facebook and YouTube.
Later in the day, it became clear authorities had deliberately blocked access to these and more than 160 other websites, as they had been used to publish images of a public prosecutor who was killed after being taken hostage by leftist militants last week.
"This has to do with the publishing of the prosecutor's picture. What happened in the aftermath (of the prosecutor's killing) is as grim as the incident itself," Ibrahim Kalin, a spokesman for President Recep Tayyip Erdogan told the Reuters news agency.
Prosecutor Mehmet Selim Kiraz and his two captors were killed after a shootout at an Istanbul courthouse last Tuesday.
Gun image goes viral
The Marxist Revolutionary People's Liberation Party-Front posted pictures showing one of the militants holding a gun to the hostage's head on the Internet, and the images were subsequently circulated on social media, before being published by several Turkish newspapers and news websites.
On Wednesday, Turkish prosecutors launched a probe into four newspapers for disseminating what they described as "terrorist propaganda" after they published the images.
President Erdogan and his Justice and Development Party have in the past been criticized for shutting down social media websites. Last year, the authorities blocked access to YouTube and Twitter after leaked recordings pointed to alleged corruption by close allies of the president.
It wasn't immediately clear how long the latest block would remain in place.
pfd/rc (Reuters, AFP, AP, dpa)