The Investigative Committee, which probes major crimes, said on March 11 that it was launching an investigation "due to illegal calls for the murder of Russian nationals by employees of the American company Meta."

Soon afterward, the Prosecutor-General's Office requested that the social media giant be branded "extremist" and called for Instagram to be blocked in the country.

The moves were sparked by a March 10 report by Reuters that internal e-mails show Meta Platforms will permit Facebook and Instagram users in some countries to call for violence against Russians and Russian soldiers after Moscow's unprovoked invasion of Ukraine on February 24.

The report prompted Kremlin spokesman Dmitry Peskov to tell reporters on March 11 that Moscow would take "decisive measures" if the story proved to be true.

"We don't want to believe the Reuters report. It is just too difficult to believe," Peskov said. "We hope it is not true because if it is true, then it will mean that there will have to be the most decisive measures to end the activities of this company."

Meta Platforms' head of global affairs, Nick Clegg, said on March 11 that the company's changes on speech in the context of Russia's invasion of Ukraine will only apply in Ukraine itself.

He said in a statement that the policies were "focused on protecting people's rights to speech as an expression of self-defense in reaction to a military invasion of their country."

He said the company had "no quarrel with the Russian people" and there was not a change on hate speech "as far as the Russian people are concerned." He said the changes were temporary and the situation would be kept under review.

Separately on March 11, Russia's media regulator, Roskomnadzor, said it will restrict access to Instagram across the country at the request of the Prosecutor-General's Office beginning on March 14.

"The Instagram social network distributes information and materials that contain calls for implementing violent actions against citizens of the Russian Federation, including military personnel," Roskomnadzor said in a statement.

A spokesman for Meta late on March 10 cited the phrase "Death to the Russian invaders" to illustrate an exception for statements that would normally have violated guidelines.

"We still won't allow credible calls for violence against Russian civilians," the spokesman wrote on Twitter.

The UN said on March 11 it was concerned by Facebook's decision to temporarily ease its policy on violent speech, warning it could contribute to hate speech.

"This is clearly a very, very complex issue, but it does raise some concerns under the terms of human rights law and international humanitarian law," UN rights office spokeswoman Elizabeth Throssell told reporters in Geneva.

Throssell warned that the new policy lacked clarity, which "could certainly contribute to hate speech directed at Russians in general."

"We may encourage them to look at certain harms that come with this change of policy," she added.

Earlier on March 11, the Russian Embassy to the United States demanded that Washington stop the "extremist activities" of Meta Platforms.

"Meta's aggressive and criminal policy leading to incitement of hatred and hostility towards Russians is outrageous," the embassy said in a statement.

"The company's actions are yet another evidence of the information war without rules declared on our country."

The embassy called on U.S. authorities to "stop the extremist activities of Meta and take measures to bring the perpetrators to justice."