South Korean police have confirmed that North Korean hackers were behind the theft of cryptocurrency worth 58 billion won, or about 41.5 million dollars, in 2019.

The National Police Agency announced on Thursday that state-sponsored North Korean hacking groups were involved in the theft of Ethereum tokens from a cryptocurrency exchange in South Korea in November 2019. The stolen tokens, valued at 58 billion won at the time, are now worth 1.47 trillion won, or over 1 billion dollars.

The police agency said that with the help of the Federal Bureau of Investigation in the United States, it was able to confirm North Korea's involvement by tracking IP addresses and by detecting the use of the North Korean language.

The police said this marks the first time a South Korean investigative agency has confirmed North Korea's involvement in cryptocurrency hacking crimes.

They added that a portion of the stolen cryptocurrency was discovered on a Swiss exchange, and after proving its origin, they were able to return tokens worth around 600 million won, or about 429,000 dollars, to the South Korean exchange.

Earlier this year, a United Nations panel of experts pointed out that North Korea carries out "malicious" cyberattacks to earn about half of its foreign currency revenue.