Customs said about 637.5 billion won ($596.02 million) worth of foreign exchange crimes were detected.
Illegal foreign currency trading of 472.3 billion formed the bulk of the cryptocurrency crimes, it said in a statement, but gave no details on what action authorities were taking against the rule breaches.
In one case, an illegal FX agency collected a total of 1.7 billion won ($1.59 million) from local residents in a form of “electric wallet” coins to transfer it to a partner agent abroad. The partner agent then cashed them out and distributed the settlement to clients based in that country, according to the statement.
In South Korea, only licensed banks and brokers can offer foreign exchange services. Local companies and residents who move more than $3,000 out of the country at a time must submit documents to tax authorities explaining reasons for the transfers. Annual overseas transfers of more than $50,000 must also be reported with similar documents.
Effective from Jan. 30, authorities imposed rules which allow only real-name bank accounts to be used for cryptocurrency trading designed to stop virtual coins from being used for money laundering and other crimes.
Among other breaches, Customs said there were also cases where investors in Japan sent their yen worth 53.7 billion won to their partners in South Korea for illegal currency trade.
It said authorities will continue to monitor for any violations of foreign exchange rules or of money laundering activities.
Bitcoin stood at $10,123.13 as of 8:42 AM GMT on the Luxembourg-based Bitstamp exchange. The heightened regulatory scrutiny around the world, however, has seen bitcoin dive about 27.1 percent so far this month, on track for its biggest monthly decline since January 2015.
Cryptocurrencies got another jolt last week after Tokyo-based exchange Coincheck said hackers stole over $500 million in one of the world’s biggest cyber heists.