Russian communications regulator Roskomnadzor stepped up its enforcement of a ban on the Telegram messaging service in the country, demanding smartphone giant Apple block push notifications from the app.

Push notifications show users when they have new messages or other activity within the app. Removing this makes it significantly less useful.

In a letter, the agency also warned Apple to remove Telegram from its App Store to avoid “possible actions by Roskomnadzor to disrupt the functioning” of the service. Russian state news agency TASS reported the regulator first sent a note to Apple and Google requesting Telegram be removed from their respective stores on 17 April.

In an interview last week, Roskomnadzor head Alexander Zharov told TASS that regulators are already working with Microsoft and Google to prevent access to Telegram, but noted the enforcement effort is an ongoing process.

The continued work to shutdown Telegram in Russia comes after a Moscow court in April banned the service for its refusal to disclose its encryption keys and grant the Russian government access to user data.

Operators in the country were already ordered to block access to the app, but enforcement efforts also ensnared Google and Amazon as Russian authorities blocked some 15 million IP addresses that were being used to access the service.

Telegram CEO and founder Pavel Durov said Russians account for around 7 per cent of users.