More than half (54%) of chief information officers (CIOs) said their firms do not allow employees to visit social networking sites for any reason while at work.

CIOs were asked, “Which of the following most closely describes your company’s policy on visiting social networking sites, such as Facebook, MySpace and Twitter, while at work?” Their responses:

54% prohibited completely
19% permitted for business purposes only
16% permitted for limited personal use
10% permitted for any type of personal use
1% don’t know/no answer

“Using social networking sites may divert employees’ attention away from more pressing priorities, so it’s understandable that some companies limit access, said Dave Willmer, executive director of Robert Half Technology.

“For some professions, however, these sites can be leveraged as effective business tools, which may be why about one in five companies allows their use for work-related purposes.”

Willmer added that employees should always use good judgment, no matter how lenient their company’s policy.

“Professionals should let common sense prevail when using Facebook and similar sites — even outside of business hours,” he said. “Regrettable posts can be a career liability.”