Trojans continue to terrorise users on the internet and must be acted against, it is said.

Graham Cluley, the senior technology consultant for Sophos, explained that Trojan viruses are on the rise, capable of harvesting information for those hackers who are more financially motivated.

He explained that they get away with using them a lot more as many times they are sent to a computer, they remain undetected for a long time, mainly owing to the fact that they do not interfere with the smooth running of a computer.

To keep them out, people need to ensure they have up-to-date anti-virus software.

Mr Cluley explained: "There are over 22,500,000 examples of malware in existence. 40,000 new examples every day.

"You need an up to date antivirus, and I don’t mean updating it every week or every day - your antivirus should be silently in the background, updating itself every hour."

According to recent PandaLabs research, the number of computers infected by malware designed to steal confidential, personal or banking details has risen by 600 per cent with respect to the same period last year.

More than half of small businesses (53 per cent) believe that the most important benefit of outsourcing is guaranteed response times for IT support. London-based Connect conducted the research in 2007.