The Herald understands two bank call centre employees, a building society employee and three other people in unrelated industries have all lost their jobs after posting disparaging remarks about customers, co-workers or their bosses.

It is a result of the growing social trend of employers venturing online, and the blurring of the distinction between public and private spaces, information technology expert Ross Monaghan says.

"There are things that are appropriate in social settings but not in a workplace setting and this is where people run into problems," the Deakin University lecturer said.

In the recent Hunter examples:

¦ A male Commonwealth Bank employee who set up a Facebook group called Rambler, since removed, and a female colleague were dismissed after posting comments understood to refer to bank customers.

¦ A Newcastle Permanent Building Society employee, believed to have written on her Facebook status update that she was sick of whingeing customers, was dismissed.

¦ Two men, working in unrelated industries, were dismissed for writing comments about their co-workers.

¦ A female employee of a retail outlet was sacked for posting comments about her boss.

Mr Monaghan said it was imperative that Facebook users "locked their sites down with privacy settings".

Users should be very careful about who had access to their pages, he said.

"This type of thing with people losing their jobs is happening more and more often as employers venture online," he said.

Newcastle Permanent chief executive officer Terry Millett said he could not comment on individual matters.

But he said the building society had a social media policy that provided staff with guidelines for appropriate computer use.

A Commonwealth Bank spokesman also refused to comment on the individual cases.

"Commonwealth Bank staff are required to abide by a professional code of practice," he said. "In instances where staff undertake activities that fall outside the code, the bank is required to undertake specific actions."

Research last month found that 11 per cent of recruiters admitted to using social media, such as Facebook, to check the backgrounds of potential employees.

Recruiting and Consulting Services Association chairman Steve Shepherd warned it was a growing trend.

Mr Shepherd said that while association members must abide by a code of professional conduct and privacy laws, publicly available information was not off limits.

"Knowing that a prospective employer may see their online persona should make people pause before posting offensive comments or compromising photos," he said.

"If it really is personal information, be sure to have the right privacy setting in place."