Rising security breaches are costing UK companies billions of pounds a year, according to research by accountants and business advisers PricewaterhouseCoopers and Infosecurity Europe.
Researchers found one in seven large organisations had been hacked in the last year and customer impersonation had trebled since 2008.
The also discovered that the average large organisation is hit by an attack every week, while smaller firms are hit once a month.
PwC says the worst security breach of the year costs a large organisation between £110,000 to £250,000 and a small firm between £15,000 and £30,000.
Jonathan Boulton, PwC risk assurance partner, said: “The UK is under relentless cyber attack and hacking is a rising risk to businesses.
The number of security breaches large organisations are experiencing has rocketed and as a result, the cost to UK plc of security breaches is running into billions every year.
“Since most businesses now share data with their business partners across the supply chain, these numbers will make uncomfortable reading for business leaders.
“Large organisations are more visible to attackers, which increases the likelihood of an attack on their IT systems.
They also have more staff and more staff-related breaches which may explain why small businesses report fewer breaches than larger ones. However, it is also true that small businesses tend to have less mature controls, and so may not detect the more sophisticated attacks.”
Organisations spend eight per cent of their IT budget on information security, on average, while those suffering very serious breaches spend 6.5 per cent, says PwC.