Russia said Friday it was opening a criminal case against Meta for "calling for the murder" of Russians, saying the parent company of Facebook and Instagram had relaxed rules on violent messages aimed at Russia's army and leaders.Russia's Investigative Committee, which probes major crimes, said it was launching an investigation "due to illegal calls for the murder of Russian nationals by employees of the American company Meta."  Russia's General Prosecutor's Office also requested that the internet giant be branded "extremist" and called for Instagram to be blocked in the country.The announcement came just over two weeks since President Vladimir Putin sent troops into Ukraine, with Russia seeking to ban any criticism of the military campaign.The General Prosecutor's Office said "materials were being distributed on Instagram that contained calls for committing violent acts against the citizens of Russia, including military personnel."It said it had asked Russia's media watchdog Roskomnadzor to "restrict access" to Instagram. Facebook and Instagram are widely used in Russia, the latter being the most popular social media platform for young Russians. Since early March Twitter and Facebook have been inaccessible in Russia.