The volume of cryptocurrency transactions funding illegal activities such as terrorism and human trafficking has quadrupled over the last five years to $20 billion, according to a report released on Thursday.

Cryptocurrencies, such as Bitcoin and Ethereum, are in theory supposed to be safer because they are conducted using blockchain technology, which creates a record of each transaction to make the process more transparent. Although it is still difficult to regulate the currency.

But in 2022, the amount of cryptocurrency obtained either illegally or for groups or individuals to use for illicit purposes stood at just over $20 billion, according to Chainalysis, a platform that provides data on blockchain technology. This is up from $18 billion in 2021, and just under $5 billion in 2017.

“The events of this year have made clear that although blockchains are inherently transparent, the industry has room for improvement in this respect,” Chainalysis said in the report.

Nearly half of the $20 billion worth of cryptocurrency payments were received by groups that had been sanctioned, mainly Russian crypto exchange Garantex, the report said.

The Office of Foreign Assets Control, part of the US treasury, sanctioned Garantex in April 2022, “but as a Russia-based business, the exchange has been able to continue operating with impunity,” the report added.

Cryptocurrency payments were also received last year by entities used to finance terrorism and involved in human trafficking operations.

The $20 billion of illicit crypto funds was also made up by digital money stolen from people or groups, cryptocurrency extorted through ransomware attacks, cryptocurrencies gained through scams and money sent to cybercriminal administrators – people orchestrating the cybercrimes.

“Last year was one of the most tumultuous in cryptocurrency history,” the report revealed.

Several large crypto firms collapsed in 2022 including Celsius and Three Arrows Capital. Most notably, virtual asset exchange FTX, which was valued a year ago at $32 billion, filed for bankruptcy in November and US prosecutors accused founder Sam Bankman-Fried of orchestrating an “epic” fraud that may have cost investors, customers and lenders billions of dollars.

But the share of cryptocurrency activity associated with illegal activity, compared to other currencies involved in illegal activities at 0.24 percent in 2022, according to the report.