Striking public servants at the Commonwealth's largest department are furious after their bosses portrayed them on a computer screen as rats.

But the Department of Human Services says the rodent ruckus stems from a simple mistake involving off-the-shelf software and it was not a case of deliberate provocation.

Anyway, it was mouse, not a rat, the department added.

Some staff are demanding disciplinary action against the manager who chose a picture of a rodent on an internal system to denote public servants who were taking industrial action.

As the department's battle with its workers over pay and conditions is about to rumble into its second year, a new icon was added to the internal online platform used to record leave, lunch breaks, sick days and other absences.

The picture denoting workers taking one-hour protected stop-work action is clearly a rodent, though the department says it is a mouse, and rank-and-file staff have not taken kindly to what they believe is being compared to rats.

One employee at the department, which runs Centrelink, Medicare and the Child Support Agency, told The Canberra Times that ill-feeling was running high since word spread of the rodent icon.

"The icon they chose to use is a picture of a rat," the worker said.

"Staff at DHS are outraged that they are being referred to as rodents by their management team.

"The decision to use a rat as an icon for ... any staff is indicative of the toxic culture in DHS management."

But a departmental spokeswoman said the angry staff had the wrong end of the stick, as the icon was chosen from those available on the commercial workplace software.

"The department uses a commercial scheduling tool to roster staff in some parts of the department," she said.

"Icons are used to designate different schedule activities undertaken by staff, and given there are already 270 icons in use, a mouse was selected to ensure protected industrial action was appropriately recorded in our system."

It was not the department's intention to disrespect its workers, she said, and the icon had been changed.

"The selection of the icon was not intended to be disrespectful," she said.

"We acknowledge it could be misconstrued, and the icon has now been changed."