The nation’s financial watchdog has found abnormal foreign exchange transactions with a total value exceeding four trillion won.

According to the Financial Supervisory Service(FSS) on Wednesday, a number of suspicious foreign currency transactions involving local cryptocurrency exchanges saw a substantial amount of money remitted abroad.

The watchdog has so far identified abnormal transactions at two major banks, Woori Bank and Shinhan Bank, totaling four-point-one trillion won, or three-point-two billion U.S. dollars.

After the banks self-reported to the FSS that some branches conducted unusual transfers overseas that initially amounted to two-point-five trillion won, the FSS began an investigation into the institutions.