Social networking on company time is costing UK businesses £14 billion a year.

The worktime lost while employees add, poke and tweet friends is having a severe effect on productivity as 55 percent of respondents to a poll revealed they access social sites while at work.

Around 18 percent spend at least half an hour a day on sites such as Facebook, Twitter and MySpace while six percent spend at least an hour – more than an eighth of their working day – on the sites.

The poll of 1,000 workers by MyJobGroup suggest not all of this time on social networks is wasted. Just 14 percent said they were less productive as a result of social media use while 10 percent said it made them more productive. More than two thirds objected to banning workplace access to social networks.

MyJobGroup MD Lee Fayer says "Our results clearly show that UK workers are spending increased time whilst at work on social media networks, which, left unchecked, could have negative repercussions on the productivity of many companies across the country.

"Whilst we're certainly not killjoys, people spending over an hour per day in work time on the likes of Facebook and Twitter are seriously hampering companies' efforts to boost productivity, which is more important than ever given the fragile state of our economy.

"Companies would do well to monitor use of social networking sites during working hours and ensure that their employees are not abusing their freedom of access to these sites."