Electronic cigarettes have been banned from use in all Department of Health and Social Care buildings with immediate effect.
The department says the move follows the publication of a report by the World Health Organisation this summer.
The report raised a number of concerns.
According to the report, existing evidence shows electronic cigarettes do not merely produce 'water vapour'.
It says they have been shown to increase the exposure to nicotine and a number of toxicants of non-smokers and those nearby.
The report adds that while in most cases the level of risk is likely to be lower than conventional cigarettes, some brands of e-cigs have shown higher levels of cancer-causing agents and toxicants.
Health and Social Care Minister Howard Quayle says his department has a duty to protect the health and wellbeing of patients, staff and members of the public visiting its buildings.