Cryptocurrencies stolen from exchanges and scammed from investors surged more than 400% last year to around $1.7 billion, according to a report from US-based cyber security firm CipherTrace. 

The report looks at criminal activity in the digital currency market.

It said that of the $1.7 billion, nearly $950m constituted thefts from cryptocurrency exchanges and infrastructure services such as wallets, up nearly 260% from $266m in 2017. 

Korea and Japan were home to most of the thefts from exchanges, or 58%, during 2018. 

The numbers on crypto theft surprised many observers given the price declines in digital currencies in 2018. 

The market capitalisation with more than 1,600 digital currencies stood at $112 billion in January of this year, down more than 80% from its peak a year earlier. 

In addition to those thefts, the research found that investors and exchange users lost about $725m in cryptocurrency in 2018 to exit scams such as fraudulent initial coin offerings, phony exchange hacks, and Ponzi schemes. 

In 2017, the exit scams totaled just $56m, according to CipherTrace. 

"These numbers only represent the loot from crypto crimes that CipherTrace can validate; we have little doubt that the true number of crypto asset losses is much larger," the cybersecurity firm said in the report. 

Thefts by hackers dominated the crypto crime scene in the first three quarters of 2018, but they were mostly about inside jobs or fraud in the fourth quarter, CipherTrace said.

"We have been seeing new types of crimes that involve money laundering," Dave Jevans, chief executive officer of CipherTrace, told Reuters in an interview. 

Jevans is also the chairman of the Anti-Phishing Working Group, a global organisation that aims to help solve cyber crime. 

"So we have seen in 2018 a lot more exit scams where companies disappear and steal people's money. There's huge increase in that," he added. 

Jevans noted that in all likelihood the bulk of the $1.7 billion in stolen and scammed cryptocurrencies has already been laundered.