A government study has revealed that computer hackers have attacked more than one in ten large UK businesses' IT services, a ten-fold increase from two years ago.

The study by the Department for Business, Enterprise and Regulatory Reform (BERR) claims that 13 per cent of large companies have activity by unauthorised users in their computer networks.

Large companies were found to be particularly vulnerable to security breaches, with 96 per cent of businesses with over 500 employees reporting security breaches.

Chris Potter, from PricewaterhouseCoopers which led the research, said: "Large corporations are being actively targeted by hackers, often working in cahoots with organised crime, and looking to steal confidential customer data which can be used for identity fraud.”

However, financially UK businesses have suffered less, with approximately £6 billion lost in 2007 compared to £10 billion in 2006, this is in part attributed to improved virus security.

The average cost of a security breach for large businesses was £1.5 million, according to the research.

A recent Connect survey found that the two major concerns about outsourcing services like IT support were 'loss of control' (56 per cent) and 'budget over-runs' (43 per cent)