A total 270 cryptocurrency addresses, many connected to over-the-counter brokers, received $1.3bn in illicit digital coins last year, research shared with the Reuters news agency showed on Thursday. The illegal use of cryptocurrencies has long worried regulators and law enforcement, with US Treasury Secretary Janet Yellen and European Central Bank President Christine Lagarde both calling for tighter oversight last month. Meanwhile the true scale of money laundering and other crime using cryptocurrencies — for example, where criminals use bitcoin to launder traditional cash — is not known.