Interpol has found a vulnerability in public ledgers to cryptocurrencies that could allow hackers to insert malware or child pornography into virtual transactions.

This is said to occur because the fixed space in the public ledger- technically known as a "blockchain" – allows malicious data to be stored in an inerasable format.

Noboru Nakatani, executive director at Interpol Global Complex for Innovation (IGCI), said: "To conduct this type of research and identify new cyberthreats were among the key aims behind the creation of the Interpol Global Complex for Innovation.

"Having identified this threat, it is now important for Interpol to spread awareness amongst the public and law enforcement, as well as encourage support from communities working in this field to find solutions for the potential blockchain ‘abuse’."

Whilst the current fears of the police unit are that the problem will be exploited to provide a safe haven for data, it is thought criminals could use it to develop modular malware.

Interpol has also warned that the tactics might change how unpatched "zero day" attacks are carried out, and also might spur on black marketplaces to sell private keys to access data hidden in the blockchain.

"The core principle of our research is to forewarn about potential future threats coming from decentralised systems based on blockchains," said Vitaly Kamluk, principal security researcher at security vendor Kaspersky Lab, which also worked on the research.

"We hope that bringing potential problems to light now will help in improving such technologies in the future and will make it more difficult for them to be used for any malicious purpose."