The Net Freedoms Project, a Russian human rights organisation, said Meta being designated an extremist organisation could mean Russian citizens being banned from using it, and businesses prevented from displaying the logos of Facebook, Instagram and WhatsApp.
People may also be banned from sending money to the company, for example by buying advertisements.
Instagram and WhatsApp are hugely popular in Russia, used by businesses as well as individuals to share messages and information.
Russian state media reported that WhatsApp could be left out of the ban because it is a communication service.
The move came after Facebook said it would let users make death threats against Vladimir Putin and call for violence against Russian soldiers, in a rare reversal of a hate speech policy.
The social network’s rules will be applied to users in eastern European countries including Russia, Poland and Ukraine.
Calls for violence against Russian citizens will remain banned. Moderators in the region have been informed of the policy in recent days. It also applies to Instagram, which is also owned by Meta.
“As a result of the Russian invasion of Ukraine we have temporarily made allowances for forms of political expression that would normally violate our rules like violent speech such as ‘death to the Russian invaders.’ We still won’t allow credible calls for violence against Russian civilians,” a Meta spokesman said.
Calls for the deaths of Mr Putin and Belarusian president Alexander Lukashenko will be allowed as long as they do not contain two indicators that a threat is credible, such as a location and method.
Meta told moderators the change was a “spirit-of-the-policy” allowance.
Facebook was banned in Russia last week, in apparent retaliation for blocking the accounts of state broadcasters RT and Sputnik in the UK and EU. Twitter and YouTube have also restricted the accounts.
The communications regulator said it had identified 26 cases of “discrimination” against Russian media by Facebook.
Facebook’s changes apply to Armenia, Azerbaijan, Estonia, Georgia, Hungary, Latvia, Lithuania, Poland, Romania, Russia, Slovakia, and Ukraine, according to emails seen by Reuters.
Downloads of Facebook in Russia have soared in recent days despite the ban, with millions in the country using virtual private networks to circumvent Russia’s internet controls.
Installations have climbed from around 13,000 a day two weeks ago to more than 22,000 in recent days, according to analysis company Appfigures.