This is how cryptocurrencies work
An estimated £3-4billion is being laundered via cryptocurrencies in Europe every year, the director of Europol has told the BBC.
It comes as the Shadow Treasury Minister, Alison McGovern, says much speedier regulation is needed.
But what are cryptocurrencies? Spencer Kelly explains all.
Watch more: Who Wants to Be a Bitcoin Millionaire? 8:30pm Monday 12 February, BBC One.