A senior Facebook chief has vowed to fight Russia's ban to ensure its citizens are not deprived of “valid and real” information on the country's war in Ukraine. Sheryl Sandberg, chief operating officer of Meta, the company that owns Facebook, said that before the onset of social media countries such as Russia were “controlled by one voice". Speaking at Expo 2020 Dubai, Ms Sandberg said Facebook had been seeking to counter misinformation from the Russian government before it was blocked. Russia imposed a ban on Facebook on Friday, as its invasion of Ukraine continued. Access to Twitter was also restricted. Russia's communication regulator said the move was in response to restrictions placed on its media by Facebook, citing 26 cases of “discrimination” against Russian media by the platform since October 2020. “Social media is bad for dictators — that's why Putin took us down,” said Ms Sandberg in a talk moderated by CNBC’s Hadley Gamble for International Women’s Day. “Before social media, in a country like Russia, the media was completely controlled by one voice. “Social media changes the ability of people to post and to speak … But, the scariest part of all of this is the lack of access. “When we go down in Russia, people are losing their ability to actually understand what's happening. So, I think we need to fight for access and make sure that social media exists so that people do get information from all over the world, and that information is valid and real.” Meta has been working on removing misinformation posted by Russian groups, including labelling posts that may be false. Ms Sandberg said that Russia had asked Facebook to stop labelling its posts as misinformation, a request the company refused. “We have been labelling things that the government says as invalid and misinformation and we were doing it in Russia,” she said. “In fact, one of the reasons they took us down is because they asked us to stop labelling those posts as misinformation and we refused. “So again, because we are not controlled by Russia, we were labelling the things they were saying that were false as ‘false’.” “I think it is a real shame that we're down and other services are down because we now don't know what kind of information is available there. It’s much more restrictive.” Meta's head of global affairs, Nick Clegg, said the company would continue to do everything it could to restore its services. “Soon, millions of ordinary Russian will find themselves cut off from reliable information, deprived of their everyday ways of connecting with family and friends and silenced from speaking out,” he said in a statement on Twitter. Major tech and social media companies have faced pressure to respond to Russia's invasion of Ukraine, which has led to economic sanctions against Moscow by governments around the world. Russia calls its actions in Ukraine a “special operation". The White House said it was “deeply concerned” by Russia's decision to block the US firm, and said it was part of a wider effort to cut off information. The ban came after Russia's parliament passed a new law imposing jail terms of up to 15 years for spreading what it called intentionally “fake” news about the military. The BBC said it would temporarily suspend the work of all its journalists and support staff in Russia following the introduction of the law.