The Tokyo-based company said Thursday in a statement that it had “detected unauthorized access to certain cryptocurrency wallets operated by Liquid.”

According to Elliptic, a London-based company that helps detect stolen cryptocurrency, “just over $97 million (€83 million) in cryptocurrency was received in accounts identified by Liquid as belonging to the thief.” In a text posted to its blog, Elliptic said its investigators are “helping Liquid track down stolen funds.”

The attack follows last week’s attack, in which a hacker stole $600 million in cryptocurrency from decentralized finance platform Poly Network, and then gradually returned the funds, claiming that the theft was only to show a security breach.

The questioner specified that he had paused the withdrawal of cryptocurrencies to assess the impact of the attack.

Digital currencies have skyrocketed in popularity in recent years, despite their volatility and concerns about their environmental impact.

Bitcoin, Ethereum and other digital currencies use a technology called a blockchain, which ensures that every transaction is recorded.

Thieves seeking to seize cryptocurrency often transfer funds through multiple accounts at breakneck speed – sometimes in hundreds of thousands of transactions – to look for clues.

However, industry players have improved their ability to identify and block stolen cryptocurrencies. For example, Liquid notes that an amount of Ethereum, equivalent to $16.3 million, has been frozen “thanks to the help of the crypto community and other exchanges.”