Russia's state telecommunications regulator said on Monday it had begun blocking access to messenger service Telegram after the service's owner refused to comply with an order to give Russian state security access to users' secret messages.
The watchdog, Roskomnadzor, said in a statement on its website that it had sent telecoms operators a notification about blocking access to Telegram inside Russia
The service, set up by a Russian entrepreneur, has more than 200 million global users and is ranked as the world's ninth most popular mobile messaging app.
Interfax news agency quoted an official at the watchdog as saying it would take several hours to complete the operation to block access. In Moscow, the Telegram app was still functioning as normal early on Monday afternoon.
Roskomnadzor was implementing a decision handed down on Friday by a Russian court that Telegram should be blocked because it was in violation of Russian regulations.
Telegram had refused a request by Russia's Federal Security Service (FSB) to give them access to users' encrypted messages.
The FSB has said it needs access to the messages for its work, which includes guarding against terrorist attacks. But Telegram said to comply would violate users' privacy.
Telegram's founder and CEO, Pavel Durov, was a pioneer of social media in Russia but left the country in 2014. He has since been a vocal critic of the Kremlin's policies on Internet freedom.
Telegram is widely used in countries across the former Soviet Union and Middle East.
As well as being popular with journalists and members of Russia's political opposition, Telegram is also used by the Kremlin to communicate with reporters and arrange regular conference calls with President Vladimir Putin's spokesman.
On Monday, the spokesman's office asked journalists who were previously subscribed to a chat in Telegram to switch to a chat that had been set up in a different messaging service, ICQ, which is part of the Russian mail.ru technology group.
© Thomson Reuters 2018