Hackers have stolen $600m (£434m) in cryptocurrency in one of the largest heists ever involving the digital coins.
The criminals struck cryptocurrency website Poly Network.
Poly Network announced yesterday that hackers had stolen around £193million of Ethereum, the world's second-largest cryptocurrency.
They also stole £182million of Binance coins and roughly £61.5million in USDC coins.
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It has urged the criminals to give back the stolen coins.
Poly Network connects together different blockchains - the digital storehouses cryptocurrencies rely on. The aim is to let the different cryptocurrencies join up, which they currently struggle to do.
Jake Moore, cybersecurity specialist at digital security firm ESET, said: "The issue with cryptocurrencies is that they are largely unprotected and therefore, when a hack occurs it is not like an ordinary bank heist where the money is stolen from the bank who remains the victim.
"Money stolen which is stored in digital ledgers is taken from individual accounts, and this is what worries those choosing to store their money in these locations.
"Simply asking the hackers to return the currencies suggests there is little left to do for those involved including the authorities."
What are the risks of investing in cryptocurrencies?
Cryptocurrency is not regulated in the UK, unlike most other financial products.
The Financial Conduct Authority (FCA) watchdog does monitor crypto, but only to prevent money laundering or funding terrorism.
That means if you put money into anything to do with crypto and lose it you will probably never see it again.
Many other financial deals are regulated by the FCA, meaning your money is protected up to £85,000 if the company goes bust or your money is stolen somehow.
This is thanks to the Financial Services Compensation Scheme (FSCS), a fund financial firms pay in to.
You can check on the FCA or FSCS websites to see if a company you are interested in is regulated and safe to deal with.
A month ago police seized the UK's largest cryptocurrency haul , worth almost £180million, after a crackdown on international money laundering.
The seizures were made by detectives from the Economic Crime Command unit of London's Metropolitan Police, and are believed to be criminal assets.
The Metropolitan Police also arrested a 39-year-old woman on June 24 on suspicion of money laundering offences. She was released on bail.
The Mirror has also previously reported that the prices of cryptocurrencies are notoriously volatile. They go up and down for many reasons , ranging from financial regulation to tweets from Tesla chief executive Elon Musk.
For example, earlier this year Musk put the word 'Bitcoin' in his Twitter biography and the price of the currency rose by 20%.
And in July cryptocurrency prices took a dive because financial regulators around the world started getting tough on the digital currencies.
