Washington,  The US has blamed North Korean hacker group Lazarus for stealing $625 million in cryptocurrency from the Ronin Network, owned by developer group Sky Mavis.

The FBI has also attributed Lazarus Group to the Ronin security breach as the US Treasury Department updated sanctions to include the wallet address that received the funds and attributed it to the Lazarus group.

"We are still in the process of adding additional security measures before redeploying the Ronin Bridge to mitigate future risk. Expect the bridge to be deployed by the end of month," Ronin Network said in a statement late on Thursday.

Ronin is a Blockchain platform behind popular non-fungible token (NFT) game Axie Infinity.

The bridge allows users to transfer funds between other blockchains and Axie Infinity and has been blocked off since the cyber attack.

"We expect to deliver a full post-mortem that will detail security measures put in place and next steps by the end of the month," the crypto network added.

In one of the largest decentralised finance (DeFi) breaches yet, hackers stole cryptocurrencies worth $625 million from Ronin in March.

The Blockchain platform and Axie Infinity operator Sky Mavis admitted the security breach, saying that 173,600 Ethereum and 25.5M USDC (a cryptocurrency pegged to the US dollar) were drained from the Ronin bridge in two transactions.

"The attacker used hacked private keys in order to forge fake withdrawals. We discovered the attack after a report from a user being unable to withdraw 5k ETH from the bridge," Ronin Network had said in a statement.

The company temporarily paused the Ronin Bridge to ensure no further attack vectors remain open.

In January this year, hackers stole crypto tokens worth $120 million from Blockchain-based decentralised finance (DeFi) platform BadgerDAO. Several crypto wallets were drained before the platform could stop the cyber attack.

In December last year, cyber criminals stole cryptocurrency worth $80 million from Qubit Finance, a decentralised finance (DeFi) platform.