More businesses are restricting employees’ access to Facebook due to concerns about productivity and security.

CNET News quotes research by security company Sophos which says that 43 percent of workers polled said their employer blocks Facebook access completely.

There’s been a rash of such reporting in recent weeks focusing on the premise that social networking sites like Facebook are bad for business.

Reports like one in the UK last month identify specific companies saying they don’t allow employee access.

That one cited an unidentified survey saying that 66 percent of UK employers are banning or restricting the use of Facebook and similar sites over fears that staff are wasting time on them when they should be working.

A report from Australia this week said Facebook costs Australian businesses AUS$5 billion a year in lost productivity.

The picture you end up with is that Facebook is a Bad Thing and prohibiting access from the workplace is and should be the default.

This is ridiculous.

Just as with early reactions to employee blogging a few years ago, blanket prohibition simply drives it all underground.

Employees who want to use Facebook will easily do so away from the workplace. They’ll do it from home, from a friend’s house, an internet cafe, on their mobile phones. There are many ways to access a place on the internet that don’t require a workplace network connection to do it.

That said, I think employer concerns about security are valid. I’m talking about security of identity in particular.

It’s quite amazing how much personal information so many people are willing to disclose online. Not only with Facebook, but in general.

I lose count of how many blogs I see where the blogger has literally his or her complete personal identity openly online. Date of birth, home phone number, where they are right now, you name it.

Sophos has some very useful information about protecting your personal identity online, including recommended best Facebook practice as well as a podcast on protecting your identity (link to MP3).

Such useful tips and tricks would be simple for an employer to incorporate into their own guidelines on social networking sites like Facebook.

Rather than prohibit access, employers will serve the organization’s interests far better by providing clear guidance to their people on safe practice. I agree with Shel: Facebook blocking doesn’t add up.

Take a leaf from IBM’s book in how they approached employee blogging – provide opportunities to involve all employees in discussion. Take a look at the BBC’s guidelines for employees – some extremely useful ideas there.

Examine the pros and cons of social networks like Facebook, from the broad business, security and professional/personal development points of view. Then you can come to some conclusions.

Guide, don’t just ban.