Crypto worth billions of dollars has been frozen as a major exchange investigates a "potential security issue".
Binance - one of the world's biggest platforms for trading digital assets - said it is establishing the facts with urgency.
Former chief executive Changpeng Zhao wrote on X that "it does look like a hack" - while co-founder Yi He said deposits and withdrawals are temporarily suspended for customers.
"User funds are safe. Binance will cover all hacking losses," she added.
According to Arkham Intelligence, which tracks the industry, crypto worth more than $5.8bn (£4.3bn) has been taken from Binance.
If confirmed, this would be the largest cryptocurrency hack to date - surpassing the $1.5bn that was stolen when the ByBit exchange was targeted last year.
After Binance's security issue was identified, digital assets worth more than $2.3bn (£1.7bn) were frozen, which could prevent the funds being cashed out by malicious actors.
On X, the exchange said its security team is "reviewing all relevant information with urgency" - and urged its users to remain cautious of scams.
The company claims it has more than 335 million users around the world.
Bitcoin, the world's biggest cryptocurrency, dropped sharply in response to the news.
At the time of publication, it was trading at about $78,500 (£58,661) - falling by 3.5% over the past 24 hours.
(c) Sky News 2026: Crypto worth billions frozen over 'potential security issue'
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