A Europol investigation has found there is no evidence linking Islamic State (Isis) with anonymous cryptocurrencies like bitcoin. The findings were published in a report commissioned by EU member states in the wake of the 13 November Paris attacks.

It has been feared that IS (Daesh) was using bitcoin and other digital currencies to transfer funds below the law enforcement radar. Although in some cases it is possible to trace bitcoins and transactions of the currency back to the sender or recipient, using it is a common way to transfer funds anonymously. Bitcoin is used by many dark web sites selling illegal drugs and weapons.

The report reads: "There is no evidence however of IS-financing networks in existence. Despite third party reporting suggesting the use of anonymous currencies like bitcoin by terrorists to finance their activities, this has not been confirmed by law enforcement."

Although bitcoin was the only cryptocurrency Europol chose to mention by name, there are dozens of so-called 'altcoin' currencies, such as litecoin, regarded as the less valuable silver to bitcoin's gold. The investigation follows a report from 17 November which revealed the European Commission was seeking to hold a meeting to determine whether terrorist cells like IS were abusing digital and anonymous payments systems to continue their operations.

Looking at terrorism funding more generally, the Europol report states: "The financing of terrorist operations has not undergone any marked changes in the recent past. The sources of funding of the operatives in the EU are largely unknown."

WhatsApp, Twitter, Facebook and the dark web still commonly used

Better known by European law enforcement is how terrorists like IS use social media to communicate. The report says: "The internet and social media are used for communication and the acquisition of goods (weapons, fake IDs) and services, made relatively safe for terrorists with the availability of secure and inherently encrypted appliances, such as WhatsApp, Skype and Viber.

"In Facebook, VKA and Twitter they join closed and hidden groups that can be accessed by invitation only, and use coded language."

Use of Tor, the anonymising browser used to access the dark web where sites are hidden from search engines like Google, is also acknowledged by Europol. "The use of encryption and anonymising tools prevent conventional observation by security authorities. There is evidence of a level of technical knowledge available to religiously inspired terrorist groups, allowing them to make their use of the internet and social media invisible to intelligence and law enforcement agencies."