Authorities with South Korea’s customs service have reportedly arrested 16 people involved in illegal foreign exchange transactions connected to crypto assets worth roughly $2 billion.

According to a Tuesday report from South Korean news agency Newsis, the country’s customs authorities plan to prosecute two unnamed individuals linked to the illicit transactions, impose fines on seven people related to negligence and continue investigating the remaining seven. Since February, the Korea Customs Service’s investigation reportedly discovered more than 2.7 trillion won — roughly $2 billion at the time of publication — tied to transactions with domestic and foreign crypto exchanges.

More than 380 billion won — $283 million — of the reported transactions were facilitated through illegal remittance agencies. According to the report, the charges on two of the individuals stem from alleged violations of Korea’s Foreign Exchange Transactions Act — legislation amended in 2017 that requires entities involved in crypto transactions to get regulatory approval from the Financial Services Commission.

Related: South Korea postpones 20% tax on crypto gains to 2025

On Aug. 18, ​​South Korea’s Financial Intelligence Unit cracked down on 16 virtual asset service providers in the country, including KuCoin, Poloniex and Phemex. The regulatory authority alleged the exchanges had engaged in business activities without registering and said it would potentially impose fines and prison time accordingly.

Following an announcement from the country’s Financial Services Commission in July, South Korea-based crypto firms must register by Sept. 24 or face possible prosecution and monetary penalties. The country’s National Assembly also has several pieces of legislation pending with the potential to impact the cryptocurrency and blockchain industry.