"The key question you have to ask yourself is, is cryptocurrency going to be developing within the central banks' scope or outside the central banks scope. And I think it's going to develop inside the central banks' scope," he told CNBC Monday.
Using digital currencies would allow central banks to have a more flexible monetary policy as well as running negative interest rates in a more efficient way when compared to the way it's been until now, he added.
European Central Bank President Mario Draghi said in October that cryptocurrencies are not "mature" enough to be considered for regulation by the central bank. He added that while innovation should be embraced and cherished, it should also be "critically" assessed.
https://www.cnbc.com/2017/11/27/global-cryptocurrency-market-breaks-through-300-billion-mark-as-bitcoin-heads-to-10000.html