The FBI has warned retailers to prepare for a wave of cyber attacks that could infect point of sale (POS) systems. The move follows the discovery of 20 hacking cases last year using the same malware that infected Target Group around Christmas, in what is thought to be one of the biggest retail cyber attacks in history.

The FBI distributed a confidential, three-page report to retail companies last week describing the risks.

The report, seen by Reuters, said: "We believe POS malware crime will continue to grow over the near term, despite law enforcement and security firms' actions to mitigate it.

"The accessibility of the malware on underground forums, the affordability of the software and the huge potential profits to be made from retail POS systems in the United States make this type of financially motivated cyber crime attractive to a wide range of actors.”