WASHINGTON (Reuters) - The Federal Bureau of Investigation said on Wednesday that North Korea was responsible for the theft of approximately $1.5 billion in virtual assets from cryptocurrency exchange ByBit.

The agency said it refers to this specific North Korean malicious cyber activity as "TraderTraitor."

"TraderTraitor actors are proceeding rapidly and have converted some of the stolen assets to bitcoin and other virtual assets dispersed across thousands of addresses on multiple blockchains," it said in a public service announcement.

The FBI said it is expected the assets will be further laundered and eventually converted to fiat currency.

ByBit said on Friday an attacker gained control of an ether wallet and transferred the holdings to an unidentified address.

The exchange caters to more than 60 million users worldwide and offers access to various cryptocurrencies, including bitcoin and ether.