Fraudsters stole $4.3bn (£3.5bn) worth of digital currency from investors and users in the first six months of 2019, challenging those who view cryptocurrencies "as safe as gold".

The spike in criminal activity is a significant rise from the $1.7bn stolen in the 2018.

In a report, American cyber security research company Ciphertrace said the stolen funds were a result of “outright thefts” from cryptocurrency exchanges, but also scams.

Hackers have also allegedly stolen more than $227m from exchanges so far this year while $851m was “lost” by cryptocurrency exchange Bitfinex.

Many of these breaches involved taking over accounts through techniques such as sim swapping – meaning the hacker receives all alerts and messages of the owner and can trade as them. Thieves also hack exchanges, transferring millions.

The other most common theft is through “typosquatting” – where victims are sent to similarly named websites after making simple spelling errors, and enter their details assuming all is above board.