The biggest IT security risk to organisations in the UK is deliberate damage by its own employees, according to research by security company Evidian.

Deliberate damage accounted for 70% of security breaches, with the next biggest cause, accidental damage, accounting for 20%.

Deliberate external misuse of systems, including hacking, was only found to be the cause of 5% of breaches.

Mark Hutchinson, director for Northern Europe at Evidian, said: “One of the biggest dangers is where an employee has handed in his notice, but still retains the right to view, and even copy, highly sensitive information on the system.”

He said the focus in most companies was still on firewalls and controlling external access, but that companies needed to strengthen their administration procedures to be able to revoke access privileges immediately if someone leaves.