Tether has blacklisted an Ethereum address with more than $715,000 in USDT, which is linked to the Multichain hack.
The owner of the address cannot move the funds, which are traced to the hack which led to a loss of $3 million.
The security violation happened on Multichain about one month ago. The project developers had warned users against the network vulnerability in January.
Three addresses with more than $160 million worth of USDT were frozen in mid-January after a directive by the authorities.
Tether started blacklisting suspected accounts following a 2017 security breach, where the company reported about $30 million worth of stolen USDT.
Tether issues stablecoins pegged to the US dollar on multiple blockchains. The digital assets aim to maintain the stability of cryptocurrencies.