MOSCOW - Russian telecommunications watchdog Roskomnadzor said Friday it had filed a lawsuit in a Moscow court demanding the blocking of instant messaging service Telegram for its refusal to provide encryption keys.

Roskomnadzor issued a warning to Telegram on March 20, threatening to block the popular messenger within 15 days in accordance with Russian legislation if it did not hand over encryption keys which give access to users' data.

Telegram's lawyer Pavel Chikov said the defense was planning to present objections to the court.

The Kremlin considers Telegram as a convenient messenger and uses it, including in communications with journalists, Kremlin spokesman Dmitry Peskov told a daily briefing.

"But the law is the law. If it is not respected, we will look for an alternative that will best meet our needs," Peskov said.

The disputes between Telegram and the government arose after the Russian Federal Security Service (FSB) issued an order in 2016, demanding all Internet service providers send to it the encryption keys of their users for the purpose of counter-terrorism.

In June 2017, Roskomnadzor threatened to block Telegram, registered in Britain, if it refused to register in Russia in accordance with Russian legislation.

Telegram agreed to do so, but it refused to provide encryption keys, which could disclose users' private data.

At that time Roskomnadzor decided not to block Telegram, but in October 2017, a Moscow court fined Telegram 800,000 rubles (about $13,800). Telegram appealed the ruling in a superior court, but lost.

Last month, the Russian Supreme Court dismissed Telegram's plea to invalidate the FSB order.

Founded by Russian entrepreneur Pavel Durov, Telegram said it has 200 million users around the world.