The mobile messaging app Telegram, created by renowned Russian programmer Pavel Durov, says it has closed 78 channels used by members and supporters of the extremist group Islamic State (IS).
Telegram said the closed channels had been used by IS for spreading their propaganda.
"As a result, this week alone we blocked 78 [IS]-related channels across 12 languages," the company said on November 18.
Telegram, a free app launched in 2013, allows messaging and content sharing among users.