Bitcoin investors were hit Tuesday by a double whammy of worrisome news from Russia, where President Vladimir Putin denounced the cryptocurrency as risky and used by criminals, and the country’s central bank said it would support moves to block websites dealing in bitcoin and other virtual currencies.

“The use of cryptocurrencies bears serious risks,” which include money laundering, tax evasion and terrorism funding, Putin said at a conference in Sochi, Russia, according to Bloomberg News. Putin called for more regulations, and said Russia should look to other nations in developing rules. He warned, though, that “it’s also important not to put up too many barriers,” Bloomberg reported.