Stuck in a recession and with no sign of a reprieve in the oil price, Russia could quickly descend into chaos if the money runs out, William Browder, a well-known critic of the Kremlin and chief executive of Hermitage Capital, told CNBC.
"I don't think you can underestimate how bad the situation in Russia is right now, you've got oil below any measure where the budget can survive and you've got sanctions from the West. Russia is in what I'd call a real serious economic crisis," he said on Thursday.
Speaking to CNBC in Davos where global business and political leaders are attending the World Economic Forum (WEF), Browder said the central bank of Russia was "running out of money."
"Let's say that they have $200 billion (in reserve) and they're burning through all sorts of money right now because of the oil prices and sanctions. They just don't have the money to support the ruble and so Russians are just suffering," he said, adding.
"Eventually they're going to run out of that money and when they do, that's when the real trouble begins," he added.
His comments come as the ruble continued its slide against the dollar. On Thursday it hit 85 rubles per dollar.
Browder was a one-time fan of Russian President Vladimir Putin but he became one of the Kremlin's biggest critics following the death of his lawyer and friend Sergei Magnitsky, who was found dead while in police custody in 2009.
Browder believes the Russian authorities were responsible for the death of Magnitsky, who had been investigating corruption among Russian officials before his death. Browder also wants an international investigation into the killing of Russian opposition figure Boris Nemtsov. Browder himself was expelled from Russia in 2005 after criticizing alleged endemic corruption in the country.