Crypto hackers have perpetrated the biggest heist ever of cryptocurrency to steal over a whopping $610 million worth of Ethereum, Binance Smart Chain, and USD Coin tokens from crypto platform Poly Network, blockchain security firm Slowmist disclosed on Twitter.

Poly Network had announced the hack on Twitter along with the details of addresses to which the tokens were transferred and also asked the affected miners to blacklist tokens coming from those addresses.

“The cross-chain interoperability protocol @PolyNetwork2 was attacked, and a total of more than 610 million US dollars were transferred to 3 addresses,” Slowmist said.

But in an unusual twist, hackers who stole more than $600 million in tokens have apparently started sending back small amounts of the stolen funds, according to publicly documented data confirmed to show the transactions early Wednesday morning.

In a transaction early Wednesday, the hacker said it's "ready to return the fund!"

Transactions publicly stored on the blockchain show an address belonging to Poly's hacker returned nearly $4.8 million in assets through three separate transactions early Wednesday.

But experts see this as a gimmick as it is only a small fraction of the amount stolen.