More than two thirds (68 percent) of UK firms believe staff using social media, such as Facebook and Twitter, in the office is a serious security threats, says Websense.

According to the security firm's Global Survey on Social Media Risks report, which was sponsored by Ponemon, just under a quarter (24 percent) have controls in place to reduce the risk social media creates.

Furthermore, 45 percent of company's don't have a policy on the use of social media in the workplace, while only 21 percent of those that do have a policy say the rules are enforced. Six in ten employee across the globe use social media for at least 30 minutes each day for personal reasons during office hours.

Networking with friends/colleagues inside a company is the most acceptable use of social media in the office, with 90 percent admitting this was a good use of their working day. However, downloading and watching videos was named as one the least acceptable use of social media in the workplace by 13 percent.

More than half (56 percent) of those surveyed believe virus and malware infections are increasing due to the use of social media, with 52 percent of firms worldwide admitting to experiencing malware attacks as a result of an employee using social networking sites and 27 percent of these say the attack was recent.

"The use of social media in the workplace is growing at a rapid pace. Savvy businesses are using blogs, social networks, wikis and other vehicles to quickly share information with their target audiences," said Spencer Parker, group product manager at Websense.

"Organisations need to educate employees about how their social media usage could impact the company, develop social media acceptable use policies, set appropriate quotas, and most importantly, invest in the right security technologies that examine the content and context of social media sites in real time."