Over 7,000 cases of suspected money laundering linked to cryptocurrencies were reported to police in 2018, the National Police Agency said Thursday.

The figure jumped more than tenfold from the 669 cases reported in a shorter period between April and December in 2017, when it became mandatory for cryptocurrency exchange operators to report transactions suspected to be linked to the movement of illegally obtained cash.

Cryptocurrency can be transferred quickly and largely anonymously, with police saying that in some cases virtual currency was used to pay for illegal drugs or child pornography.