Pavel Durov, the billionaire founder and CEO of the Telegram messaging app, has repeatedly run into trouble with both the Kremlin and Western officials as he cast himself as a champion of free speech.

Russia’s main domestic security agency said Wednesday that Pavel Durov, founder of the messaging app Telegram, has been charged with “aiding terrorism” and put on an international wanted list.

The Federal Security Service, also known as the FSB, accused Telegram's administration in a statement of failing to remove "numerous channels, chats and bots" that are "actively used by Ukrainian inte...