Russia's communications watchdog threatened on Thursday to block access to popular VPN services which allow users to gain access to websites which have been outlawed by Moscow.
Russia has introduced tougher internet laws, requiring search engines to delete some results, messaging services to share encryption keys with security services and social networks to store users' personal data on servers within the country.
But VPN (virtual private network) services can allow users to establish secure internet connections and reach websites which have been banned or blocked.
Russia's communications regulator Roskomnadzor said it had asked the owners of 10 VPN services to join a state IT system that contains a registry of banned websites.
If the VPN services link to the system, their users would not be able to reach websites which had been blocked or be able to use the banned Telegram messenger service.
The internet censor said that it had sent notifications to NordVPN, Hide My Ass!, Hola VPN, Openvpn, VyprVPN, ExpressVPN, TorGuard, IPVanish, Kaspersky Secure Connection and VPN Unlimited, giving them a month to reply.
"In the cases of non-compliance with the obligations stipulated by the law, Roskomnadzor may decide to restrict access to a VPN service," the watchdog said in a statement.