Workers who conduct personal relationships during office hours could be costing their employers £10bn a year, a new report has found.

The research, conducted by YouGov and business advisers Croner, found that over a third of employees use office equipment for personal means.

Email was the most popular way to communicate with friends and relatives, with 22% of respondents admitting to using it to conduct a personal or romantic acquaintance.

Work landlines came second on the list at 21%, with personal e-mail accounts coming in third at 18%, and social networking sites fourth at 11%. Work mobiles came in last, with just 6% using them for personal calls.

Surprisingly, men were found to be more likely to use work equipment to keep in touch with their loved ones, with 39% saying they did so daily, and 7% even admitting to doing so at least once every hour during the working day.

Geographically, people in London are most likely to be found making personal calls during work hours, with Scottish workers least likely to be doing so.

Gillian Dowling, an HR expert from Croner, said it was important to have clear rules in place so workers know when they are overstepping the boundaries.

“Most employers will allow staff to make the odd personal call or send a few emails during the day within reason, but if they don’t set clear boundaries, the potential for company losses in terms of both time and money is almost limitless,” she said.

“Employees should remember that there may be no such thing as a personal call or email if it is made or sent on equipment owned by their employer.”

“Staff need to understand what is and isn’t seen as acceptable personal use of company equipment, and what the consequences are of stepping outside these boundaries,” she added.

© Crimson Business Ltd. 2008