The environmental health offices at Dublin City Council had to be shut down after rats infested them.
Staff at the offices, responsible for policing cleanliness in businesses, including restaurants, around the city, were sent home for a half day after the rats were discovered last week.
Rodent control personnel were called in and six rats were discovered on the ground floor offices at the council's plush Wood Quay development.
A spokesman for the council said: "There were a few rats discovered on the ground floor section. It has never happened before. The offices weren't shut, the staff were relocated to another office and some were sent home for a half day.
"The rodent control people didn't know quite why the rats were in the building but they suggested that the wet had washed the nests away and that the rats were relocating."
Fianna Fáil councillor Mr Chris Andrews said the fact that the rats had inhabited the office in charge of making sure they are kept under control highlighted the extent of Dublin's rodent problem.
"If anything this really highlights the rat problem in Dublin. People should take precautions and be aware that there are so many of them in the capital and that they appear to be on the move indoors at the moment.
"Dublin City Council needs to take a serious look at the rat problem in this city. The fact that they infested the environmental health offices should really bring the problem home to the council." Staff were ordered to move from their desks last Thursday after council officials were informed that a rat had been seen in the ground- floor offices.
Further examinations of the area showed that a number of rats appeared to have taken up residence in the environmental safety hub of the city.
A rodent control company was later called in when the offices were evacuated and they discovered a number of rats, including one that was pregnant, living there.
The council says it has since sorted the problem and the offices are fully operational again.