Bitcoin extended losses for a third day, tumbling as much as 12 per cent Sunday as South Korean cryptocurrency exchange Coinrail said there was a “cyber intrusion” in its system. The largest cryptocurrency declined to US$6,840 as of 4pm in New York, the biggest drop since March 14, according to data compiled by Bloomberg from Bitstamp pricing. That widens Bitcoin’s losses for the year to 52 per cent. Peer cryptocurrencies Ethereum and Ripple fell 10 per cent and 11 per cent, respectively. Coinrail confirmed in a statement on its website that some of the exchange’s digital currency appears to have been stolen by hackers, but it did not quantify its value. Coinrail only said that it was cooperating with investigators and other exchanges to try and track down the perpetrators and recover the money. There’s a bitcoin bubble, says Alibaba executive chairman Jack Ma The central security problem with digital currencies is that the money itself is typically represented by little more than a unique numerical code, which means the owner is wiped out if that data is ever stolen. Coinrail said it’s reviewing its system due to hacking attempts. The exchange said it has managed to freeze all exposed NPXS, NPER and ATX coins, and that other cryptocurrencies are now being kept in a cold wallet. The statement is the only content available on the exchange’s homepage, and contact information could not immediately be located. The exchange trades more than 50 different cryptocurrencies and was the 98th largest, with a 24-hour volume of about $2.65 million, according to data from Coinmarketcap.com.