Original source is
http://www.gazeta.ru/business/news/2015/07/14/n_7376709.shtml (in Russian of course). Google translate (unedited):
Russian President Vladimir Putin believes that the use of Bitcoins and other cryptocurrency acceptable. Such a statement the president made during the educational forum "Territory of meanings on the Klyazma" is a live broadcast channel "Russia 24".
"They are in no way provided this money, that's the whole point, is the main problem. They are useless and do not really tied in no way guaranteed. But in general, as the unit of account as they're called, "coin", they can be used, they are more and more widely spread. Like any equivalent in some segments of calculation, probably, probably, "- said the president.
Earlier, Putin spoke about "Chocolate period" in the economy.