Employers can read private messages sent over the internet by workers during office hours, European judges have ruled.

In a case put before the European Court of Human Rights (ECHR), judges ruled that a company which had read an employee's messages sent through Yahoo Messenger while he was at work was within its rights to do so.

The ruling said the man, an engineer in Romania, had breached company policy and his employer had a right to check if he was completing his work.

The decision highlights the growing issues social media and internet misuse causes employers in the workplace, says Ashley Harkus, head of employment, at Newport and Pontypool law firm Everett Tomlin Lloyd and Pratt Solicitors.

He said: “It is vital that employers agree a social media and internet policy with their staff to set the boundaries of acceptable use.

“In this case the court held that it was reasonable for an employer to monitor social media use in work time as the employee had been using chat software on the employers IT system when they had a blanket ban in place.

“An increasing number of employers are now taking a more flexible approach to personal use of the internet and social media in the workplace to reflect modern life.

"Employers need to decide where the line is to be drawn, draft a policy clearly explaining the permitted use of IT owned by the business and the use of personal devises in work time and clearly set out the steps they are entitled to take to monitor compliance and the sanctions for misuse. The policy should then be agreed with employees and incorporated into their contracts or handbook.

“With a clear policy in place both employee and employer should be aware of their rights and responsibilities and costly disputes can be avoided.”

The ruling affects all EU countries which have ratified the European Convention on Human Rights, which includes Britain.

In passing down the ruling, the judges also said that unregulated snooping on employees would not be acceptable, and called on a set of polices to be drawn up by employers that would clearly state what information they could collect and how.