Upbit, South Korea’s largest cryptocurrency exchange, reported a security breach early Thursday in which about $30.4 million (44.5 billion won) in digital assets were transferred without authorization from one of its hot wallets, an online storage system used for real-time digital-asset transactions.

Deposit and withdrawal services have been suspended while the company conducts a security review, and Dunamu, Upbit’s operating company, said it will cover the full amount using company assets. Financial authorities have launchedan on-site inspection, and Upbit said it has frozen about $1.6 million (2.3 billion won) of the stolen cryptocurrency on the blockchain while tracking the